Evolution journal V34

b'.Ofe(YV^rc^ Vol III No MAY, 20 Cents 1932 EUOLUnON A JOVRTSAL OF NATURE Keystone-UndeTwood Photo WHAT MADE THE FLOWERS? (See Page 3) EVOLUTION Page two Scientific Advisory Board Anton Henry Carlson J A to Katterfeld two additions note will editorial Prof A J Carlson, Head of Physiology DepartChicago University, joins our Scientific Advisory staff ment of in natural science OVEN now becomes one of our Contributing Editors Readers who know Professor Carlson and Dr Ward will already appreciate our jtart in securing their active co-operation TN RESUMING appreciation our express of science freedom friends this possible was merited whose contributions to manv have made the We shall strive to prove that their confidence We hope not only to bring Evolution out reg- but to ularly, of first make it a still T7VEN if '"^ would be need and a that being done is at all there for a natural science journal field "easy to read" and always accurate is work fuss now and more More research exploration parties are in and Evolution will help to pass along There is too great a information newly-found their spread between what the scientific world accepts and knows, the field than ever before, It needed is all the more So, we urge every one of hundreds of new ones that started again, with this issue, to become active supporters of this great The most immediate task double the present to is make paid circulation of Evolution, so as to show it your friends and secure a to journal the Please not keep this copy to yourself, but self-sustaining tion subscribers And, if little possible, also new Evolu- club of contribute a NEW EVIDENCE FOR EVOLUTION Perhaps the most impressive evidence for evolution many that so fact fields different lines of evidence of investigation If there clusion check Evolution's educational campaign to be used in independent made no fundamentalists the Evolution has our old readers, as well as the a ganized superstition days of depression the work of popular these in that better instrument for arousing more general interest in natural science, and a more effective champion of science teaching against the forces of or- II a matter of surpassing importance It is race education must go on work we wish support the for human of the Dr Henshaw Ward, author of "Evolution for John Doe" and "Charles Darwin: The Man and his Warfare," publication of Evolution Maynard Shipley Henshaw Ward Horace Elmer Wood cated by the fact of evolution, would have upon the endeavors Board good fortune Edwin Tenney Brewster Pauline H Dedereh Carroll Lane Fenton combat bigotry and superstition and develop the open mind Evolution's to Contributing Editors Journal of Nature For popular education Managing Editor YOU Allan Broms EUOLUTiON Elihu Thomson E 1932 Science Editor E Crampton Martin Dewey Wm King Gregory Paul B Mann L May, all from point to the is the entirely same con- was only one chain of evidence, then a "missing link" might be of some importance But this loses significance entirely in view of the multiplicity its of inde- pendent proofs In new issue this we present evidence from a comparatively Darwin and Huxley knew of research, about which field nothing practically And yet everything that is being dis- and what the mass of the people understand Evolution We hope also that teachers will help to bridge this gap covered today supports the view of these old masters, that Evolution own fields logy in the article by Professor Robert Hegner In our next and scientists, useful for BUT busy with reliable its fundamentlism their specialties, will find information outside their is neither dead nor asleep Funda- mentalist magazines are constantly agitating their readers regarding "dangers" the "real" scientists are them popular mendous And discarding the "theory", and preparing for the promised through in effect campaign referendum at present outlaw evolution teaching to vote This influence through teaching in the has thousands of school administrations, as for instance in Boston, medievalism is in the saddle I -^ 'HE only solution for this education in natural science and prevents the High problem When of people have some inkling of what is is general a sufficient meant by a fact all popular number a scientific approach to a question instead of accepting opinions dogma- handed down by authority, this situation will change There is literally no way to measure the far-reaching effect tically that a general recognition of man's place in nature, as indi- We refer to the evidence from Parasito- the article by Professor H Gideon Wells will bring more new evidence from Biochemistry Although for some of our readers we perhaps it may prove rather are sure they will find it will also difficult to it master this mater- eminently worth while prove entertaining to bring this new And evi- dence for evolution to the attention of fundamentalist friends SCIENCE CONGRESSES tre- schools School biology teachers from dealing with evolution at ' that is issue ial, them assuring of evolution, evolution Three Science gatherings this summer will interest readers of Evolution American Association for the Advancement of Science at June 20-25 Particulars from Permanent Sec'y A.A.A.S., Smithsonian Institution, Washington, D C Syracuse, N Y., International Eugenics Congress at American Natural History, N.Y.C., August 22-24 ternational Congress of Eugenics, International gust 24-3 L Museum of Address: Third In- Cold Spring Harbor, N Y Congress of Genetics at Ithaca, N.Y., Au- Information from C C Little, Memorial Laboratory, Bar Harbor, Maine Sec'y Jackson EVOLUTION, May, 1932, Vol Ill, No (Whole No 19) Published monchlv by EVOLUTION PUBLISHING CORPORATION, 200 Varick St New York, Editorial Address: Route 4, Hempstead, N Y Application for Second Class Entry pending at Post Office, New York, N Y Single subscription $2.00 a year; additional subscriptions $1.00 each; Foreign, 10c extra; Single copy, 20c; bundles of 12 or more, l/3c per copy — May, EVOLUTION 1932 What Made asks what made the leaves of plants, he is proposing a question that has no answer, for no one can how tell happened leaves know botanists come to "What made that into is and delicate tube, so small that through the core of the can force a passage down it silk thread, dissolving, really eating, But its way along one of the its nucleus combines with the nucleus of the waiting egg existence the flowers?" the Flowers? HENSHAW WARD By TF ANYONE Page the whole length until At what then? moment reaches the egg There it corn made comes one of the hundreds of juicy kernels that are the flowers Before a flower There is answer can be understood, we must know what this It is an apparatus by which plants make is seeds a bewildering variety of flowers, working in various common ways; but the most kind, the kind with which this One of two organs article deals, consists At of an embryo which are in the of pollen male element, the sperms, the to organ, called a is a knob These grains correspond the top of the stalk of a stamen fine grains The animals in second produces the female element that goes to pistil, making of an embryo At the base of the surface of the cob If but stalk its which contains eggs that are waiting to be is an ovary fertilized it is allowed to grow hard, is the a new is kept through the winter, and Thus we see that a corn plant alone in own its of pollen, and is sprout and grow into complete within is pollen If and stamens Some The plant its could be it Yet self- an ordinary in tassels are ripe, the air Such is by pollen pollination called is plants cannot be fertilized by their and experiment has shown and surely itself: one cornstalk stood silky pistils are fertilized blown from another plant pollen; more pistils many "cross-fertilization." own own its on a windy day when the cornfield, that will midst of a large space, the sufEcient with full it cornstalk ovaries are fertilized by all on set not gobbled by hungry animals, put under ground next spring, of these, called a stamen, produces the male element that goes to the making created is And embryo of a new kernel of This grows as the weeks pass until it be- that most pregnant queries ever put by a naturalist, and that the answer is the prettiest one in the domain of evolution Insects richly fertilized most plants are that by the pollen from another general rule of nature is most plants that quire, or are better off with, cross-fertilization re- Grasses and send out in the spring vast numbers of pollen-grains, trees which the air in uncounted millions fill The pine, for ex- ample, commits to the breezes a kind of pollen-grain that is wafted by means of air-sacs on either side of it Perhaps only one in a million finds a Botany for Colleges — Ganong: Macntillan left, Salvia pratensis, hinged lever arrangement brings stamens down on body of bee Moth in Yucca flower at right, carries pollen from another flower, tamps it down and lays egg in it In flower at you look If you closely at a typical flower —say a is stalk that bears aloft little pistil It is a fearfully extravagant succeeds It accomplishes the cross-fertilization it that plants are in need of Plants with conspicuous They have found lure a wild rose will see at the base of the colored petals a circle of several dozen stamens, each of which method, but is and bribe flowers a cleverer insects to are not She business of every stamen the nectar that she can convert into honey some pistil; to convey it process of fertilizing of pollination its is to capture a pollen- egg Unless the egg barren and cannot produce by pollen, is is called the origin of is "pollination." On means dozen rows of the cob of the pistils is fertilized pistils the "silk" of the ear Two air feet the "tassel." When microscopical grains float open and pistil call this set down through of them lights on the tip of a thread of transformed into a of above the ear at the spill thing of life their the nectar we contents When air silk, it is It sends out a that That flies it to the into the a sip is of she all But the flower has quite other thoughts to another flower As The she presses eagerly forward some of the pollen-grains that she has been transporting are rubbed off and gathered in bv call mating-time comes for the plant, the pollen-sacs of the tassel — for the next drop of nectar, top of the cornstalk, was a cluster of stamens, which knows quickly sticks some pollen-grains on to the bee's head need the bee that it certifies She confidently runs her tongue And From each We thinks of It because of one of the flowerets, and finds, sure enough, bee extended a long, delicate thread, which reached to the end of the cob and stretched out into the presence of food likes the odor, This you can realize what pol young ear were clustered waiting to be fertilized advertises food a seed the colored flowers all If you think of an ear of corn, a pollen to the top of the purpose of every pistil grain that will fertilize lination its this buzzing up to a head of clover She has been attracted by the bright red spot in the landscape, for she bell is They pollen the carrying Watch Within this' circle of stamens is a cluster of pistils; each of them is rough and sticky on the upper end of its stalk, and each one terminates below in an egg-sac The pollen-sac its extravagant so way of conveying The one straightway most slender the rough, sticky tops of the greedy pistils The unconsciously, accomplished cross-fertilization If botanists pollen for knew only of clover and roses bee has all for the clover the ways in which insects carry and buttercups and lilies, they would never suppose that they knew the answer to "What made the flowers?" They might guess that these four flowers had developed, through a long course of evolution, such showy and sweet-scented mechanisms taste as were adjusted to the of insects, that the blossoms had been gradually shaped by the success of those plants that varied grow more and more in attractive to insects It such ways as to might be a likely guess that insects, by avoiding the less pleasant flowers and — EVOLUTION Page four visiting more pleasant ones, had the But preferences would be only a guess this had studied thousands of naturalists Until of species many plants for almost a century, they were not well-enough informed to establish a reliable theory of But how made the flowers much knowledge of the insects ago they had acquired so sixty years the relations of plants to insects that they felt pretty confident — Think and shaped actually colored and given odors to the blossoms that catered to their May, of a flower whose stamens "wither before the pistils The are ripe for pollen It can never fertilize itself would species die next year if the blossoms did not succeed in entic- come ing bees to in 1932 A them to which the stamens have bee has been visiting blossoms on her skilfully deposited pollen head; she comes to these waiting that are surrounded pistils by dead stamens; she rubs off pollen on them; the flowers are No fertilized had botanist can conceive that a flower has remarkable adaptation from the beginning of time; which Darwin first added knowledge of botany confirms Darwin's theory, and no knowledge has run counter to it Today every botanist as- species sumes that flowers were developed, to suppose that all flowers which varied toward ment were more have descendants that would con- of the theory of elaborated Since then all in the course of millions by the adaptations that plants made for inviting years', and employing and rewarding the we can look In this brief article this must have evolved few examples of those thousands of devices which have been evolved by plants A to realize the meaning of the juice of flowers, the nectar, is made; and honey nature; honey is for mind The (1) if sweet from which honey the material the only food of bees in a state of is and death They honey, and store it in the them a matter of drink the nectar, convert comb is devices it into life to support life through the winter Pollen (2) is the source of the "bee bread" on which the young bees are fed (3) The whole duty incessant labor so long as they live pollen to the combs — — of worker bees (4) to is to bring nectar and of a worker is an apparatus for extracting, carrying and converting the food that found is bee are in flowers The mechanisms and directed to one end: all instincts of a successful visits to (5) are, like the bees, engaged when they visit in the most serious business of blossoms: if they not secure And it is equally true of all those flowering plants which depend on insects for pollination that they will die if they not persuade the insects to visit them Flowers and insects are engaged every minute of their lives in an unrelenting struggle to exist If we find them adapted to each other's needs, we can be sure that the adaptation is not a chance and not a joke; it must be a result that has evolved in the course of the long ages of fierce competition to survive open a flower which does not at light yellow color that has a strong odor; can only imtil nightfall It It has the it starlight; it bottom of a long tube at the need of bees or its time of opening, odor, position of nectar color, Its are adjustments to invite a certain kind of night-flying all moth to is could never have been developed by wasps — most prominent in the is nectar its All what and habits have evolved structure its this moth as a response desires There are many plants that have developed ways of ing out unwelcome ants from the store of nectar bristly or tanglefoot Yet hairs — fenc- barriers of so con- are flowers these structed as to admit the long proboscis of the bee They have been shaped in a complicated and accurate way by the attacks of enemies and the of friends visits In some flowers the petals form a cap over the stamens, and cap this is so delicately adjusted that which arrangement is touched is a set sets next flower she One of the set of stamens in another provided with a trigger, so proboscis stretches thrust aside and dust her with pollen, visits Another similar of stamens that fly up and strike when their base flower is the chest, in will fertilize the is it Instantly the released stamens fly by the landing of a bee up, strike the bee food, they die We further in that direction still arrange- this has no gay colors, for they would not be visible; All insects that depend on flowers for a living flowers their lives making likely to to the tastes of insects itself which they devote The whole anatomy is imagine that the species was thus transformed by adjusting Look of five facts should be clear in a reader's series is there tinue to vary insects at only a in their efforts to use insects as pollen-carriers he And it some period in the history of the no way to imagine the evolution except at down for nectar that set it when the bee's strikes the trigger and the stamens to vibrating all When you see an orchid in a florist's window, you are look- ing at one of the family of plants that have gone furthest in inventing machinery to work tricks on bees One of them actually provides a pool of water, on the brink of which is — ^sac.?^ "^^5-_ some food that bees are eager to gnaw so eager that they often push each other into the water! When their wings are draggled, they can leave the flower only by a the overflow spout In tunnel the pollen this is tunnel near stuck to their backs, and so will be carried to another flower and fertilize In some of our American swamps there is a delicate flower called "sundew," because on the surface of there are drops of sparkling white its These drops are so it little leaves sticky that they can hold on to the feet of insects; the hairs on the surface of the leaf then fold over one by one and strangle the insect; the plant digests of very different kinds, victim It has evolved a trap its' digestive fluids that enable it Way Passage" of bee through lady-slipper flower Many For example, the butterwort — which has to rely other by snapping leaf-edges over them while insects on and other plants, have developed other methods of catching and eating insects "One to eat meat insects for carrying feet are caught in a viscous fluid its pollen captures their May, EVOLUTION 1932 There are African plants soms a foot in and smelling They diameter the odor resist unpleasant in color, in shape, meat when the rotten like disagreeable are inunense pulpy blos- that have —ugly human to need pollen pistils but beings, Flies visit flower after flower, carrying them pollen that clever stamens load pollen on the eager The pistils promises carrion on which b a swindler; for can lay eggs, but flies nothing This curious adjustment of a flower coaxes It down to crawl flies throat its through a ring of hairs that point quite easily pass gives it meet the to England, plays another kind of rascally flower, in confidence game They it can only be a produrt of gradual evolution instinrts of flies Another the with, brushing off the plant downward, but they cannot climb out again because those hairs are now pointed at them and block the way A fly thus imprisoned must wait until the stamens ripen and dust him with pollen Then the flower pays its bill with a few same drops of nectar; the hairs shrivel up; the is down throat of another flower the appropriates the pollen it fly escapes and soon that captures brings If all it and were teachable flies and there tamps it liging? Because she down carefully Why is making a place to the egg hatches, the larva eats Such a marvelously caimot flies Page seems purposeful It some of the is is doing But of course she has For every such provident action by an insect a matter of inherited which instinct, knowledge of what the result to be is tically useful to each party An illustration roman- is a yucca called is Spanish bayonet that grows throughout the Southwest entirely which dependent for collects pollen, carries it It is on a small white moth fertilization to the pistil of another plant, known is to be obeyed without any The the favorable variations of stamens and were adjusted to each other desire instinct could only pistils The and egg-laying plant that furnished more enticing pollen would have more descendants; its type would increase in numbers and would tend to produce still more enticing pollen Likewise the moth that managed the more likely to have successful descendants Each plant or insect that inherited a tendency toward better co-operation was more likely to have offspring, and these pollen best was descendants were increasingly likely to inherit the plants to fertilization by insects between flower and insect is have been developed by a process of evolution, in which Flowers have been adjusted to the peculiarities of relation seeds, but not all of plant to insect not done, she could not conceivably do, anything of the sort made Sometimes the so ob- When hard to believe that the moth has not reasoned out what she and would not venture a second time into the kind of flower that had deceived them, no such trick could have evolved insects lay exact adjustment moth an egg the is five co-operation still traits that nearer perfect This theory can explain every case of the adaptations of for the adaptations his No other theory can account who there were a botanist rejected seemed too miraculous, he would have to scholarly work in the dark All his fellow botanists the theory because live in If it the light of a theory that helps nature operates They can see how them understand how insects made the flowers The Tale of the Horse ALLAN BROMS By /^UTWARDLY ^^^ we see little likeness between the horse, but inwardly they are much alike man outwardly, that the horse has four legs and What we forget, for the moment, is that man's man and We see, but two not even recognised as an early horse have a very complete fossil Now, record, largely Western bad-lands, where the however, we dug out of our arid soil lacks grass roots to arm was, not long ago in his evolutionary history, just a front leg which has become arm only recently by his uprearing to the erect attitude him But let a horse uprear that way, then look through skeleton, to his nearly every part the skull, arm and you and the horse has bones will see the resemblance in Proportions have changed, lost some teeth, Otherwise they are strikingly especially and alike in leg and At the American Museum of Natural History you can make this comparison, for they have mounted the skeletons of a man and a rearing horse side by side The marked likeness shows our remote kinship, while the differences are important in their emphasis of the recent evolutionary changes which made man a man and the horse a horse But here I The Tale of the Horse The horse is distinctive in having but one toe will tell only to each Both are parts of the same Already, back in 1870, Thomas Henry Huxley, the story great evolutionist, realised what that story must be and forefoot and in his unusual teeth told that we should find the fossil remains of a series of in- creasingly horselike creatures that began with a normal five- toed animal time only one having just ordinary fossil mammal teeth At of this series had been found, but it that was Courtesy Modem Amerian Museum Horse Compared with of Natural History his early ancestor, Eohippus Page six bind It EVOLUTION and the occasional rainstorm torrents cut away quickly, exposing the fossil bones species have been found, most of them side together soil the loose Dozens of We branches on the family tree of the horse few a very stick to mean- along the direct line of descent Eohippus, "dawn ing the must Epoch, some horse," is hoofed animal There were not five toes this least folks with ancestors, he has now beginning, we can geological came on progressively up through which for us means up through the geological epochs, AjicmUli'ium '(Europe much each foot, the two side toes were getting smaller and weight was carried on the middle toe Hypohippus came a bit later, as large as a pony, its middle toe looking the And "nearly lost" them, for bones now so time today have nearly and change went on lost their Now horse of today reverts to his ancestors and toes on his more are on feet side toes is say, splint and then some born with extra Caesar owned such a Julius until I remnants remain as the two entirely buried in the flesh America)- aii-f D/orlri Lar^t i-Totd \ Lar^t: \ l-Toed ^ and\£urope)-\ ^Nartlt America Asia Mype/iipptii (NcrU AmeLct) ParaJiippus Mtr^entppui ' (Ka,,), America.)- Proto/lippui (No-rf America)- - - -*-ô|B H - -I America)- (A^m/ri H'ppidiun already the size of sheep, and though they had three toes on a hoof i Fofi \STvalI '- - ]'* -,- - strata or layers Orohippus, the "mountain horse", were just a bit larger than horse", and Epihippus, the "upon Miocene Epochs, about and Oligocene By the Eohippus twenty million years ago, Mesohippus and Miohippus were like are all Mnohtppui lS)iatli Onohippidiu^ Hippu n - horse and record - -( i: consistent with swiftness the horses of we all, Orchippui- Pttonippu of the earth crust, for the top layers are of course most reThere was an increase in size, but only up to a limit cent more himself After it Epihtppui trace the changes that the of reason to take pride, for little he had nothing to with on His brain was well developed for his time, a sure sign he was active and swift, to make up for his smallness From on the horse; he has a pedigree that stretches But properly, like other fifty million years states, a foot, he was too fat along in his evolution for that, but he did have four on each front foot and three on each hind that back at none can ride talk about your old families, but the high horse Smu/l 4-Tord UorifS' Western years ago, in our where the evolution of the horse seems to have occurred He was somewhat larger than a big cat and had an arched back However his feet and teeth were not cat-like, but belonged foot You may 1932 the earliest, living during the Eocene fifty million to a browsing, May, — V America f (S^outfi America hotlh America Ana Eurbpc and A/aiM A^nca)- > {A'ef:r> 1,11.1 Sai^rf' An Furope iiiia |/i]/fl i^iid Courtesy American Af>, Museum Natural History of Geological and Geographical range of ancestors of horse show life creatures span of each genus conditions, of make demands that variations change in not, our careers end A When made by our environments which we must needs meet, us Black lines Dots, show line of descent the or die out right directions, we If our survive, if change of climate made the horse Eohippus made the our Western country was start, low and swampy, just emerged from the sea, for the earth was crust here The rising climate was moist and the country woods, Eohippus hid, alert and on the get-away when he was discovered His coat may have been striped like a zebras to help him hide His wide, three- and four-toed feet kept him from sinking into He browsed on leaves, which are soft, so the soft ground In forest-covered these quick his teeth were a browser's teeth, more like those of a tapir than a modern horse But not only were the swampy forest lands rising; a mountain range was being uplifted to the West, cutting oil the moist winds of the Pacific, causing a dry climate which Slowly the woodlands gave way to and the horse found himself out in the open, many dangers, among them a shortage of leafy discouraged the forests the grasslands, exposed to food To had to acquire speed survive in this environment, he for escape and for rapid ranging for his food supply, and had to develop teeth for grinding grasses became close a grazing cutting bridle conclusively that Then came bits leverage, came pattern, plex a And way Up horse perforce The front toothless dis- became sharp for where we place our they space, back, where the jaws have a strong the grinders tough, hard food The animal instead of a browser His teeth They became strong, fitted for grinders have rough surfaces of com- due to unequal wearing down of the twisty and the soft dentine alternating edges of glassy-hard enamel and cement between In the early horse, the surface patterns were simple, but as they evolved, the patterns became complex and more horse-like in the modern sense Also they became longer in root and crown, permitting them, after their oriCcurlcsy Muieum of Natural History Hind Foot of Horse Miohippus, Merichippus, Hipparion, Equus Evolution of Eohippus, Mesohippus, American ginal growth to maturity, to for many teeth move instead of years as their surfaces wore down became fit for cutting grow outward Altogether, the and grinding great quantities of May, EVOLUTION 1932 Page seven much bulk An- feed hard and relatively innutritious grasses of the plains, instead ing grasslands, there being just too of the soft green leaves of the forests Necessarily the horse, other relative, the tapir, had specialised too well, found him- order to survive, eventually had to become a grazer with in new kind of the remained browsers for the in cling In the end the horse also died out in America where he changes Eohippus was down making know how and on really heavyfooted, foot-weight handicaps, his tip toes, his had a rid tie of bones lot of this excess the horse literally light-footed If you want to weights on your ankles Another aid was that even Eohippus walked try to run really were also important for he But evolution slowly got in his foot weight, Increased size helped, leg machinery his in way up for the horse's hock, half On heel the dry, grassy plains, the his leg, is ground was hard, and even the narrow hoof of the middle toe would not sink in Besides there was it and other joints been gotten rid less on rough ground when the wide foot had of The joints themselves also changed to he need put forth no effort to keep his legs straight sideways, to give He With such is all his muscles can be devoted to moving forward, him speed Mechanically, he "on light-footed, toes," his a marvelous adaptation is without waste muscles, enemies, to cover a wide grazing range Nature made of the horse new hard and latives swift to survive went in for experiments also worth more in with in the it was a rhinoceros, small his the severe struggle brainless relatives several but somehow on feet, bulk, the Some not of good the re- in than dead, when he harnessed the horse's on the strong back and We5leni.Unite