Bulletin of Museum of Comparative Zoology 45-2

Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE Vol XLV No THE ANATOMY OF HEMIURUS CREyi\Tr5f' (RE'D^ LUKE, AN APPENDICULATE TREM/TODR By Clarence With Four H Landeb Plates CAMBRIDGE, MASS., U.S.A.: PRINTED FOR THE MUSEUM January, 1904 Bulletin of the Museum of Comparative Zoology AT HARVARD COLLEGE Vol XLY No THE ANATOMY OF HEMIURUS CRENATUS (RUD.) AN APPENDICULATE TREMATODE By Clarence With Fouk H Lander Plates CAMBRIDGE, MASS., U.S.A.: PRINTED FOR THE MUSEUM January, 1904 LUIIE, No — CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, UNDER THE DIRECTION OF E L MARK, No 148 TJie Anatomy of Hemiurus crenatus (Rud.) Lilhe, an Appen- Trematode cliculate By Clakence H Lander CONTENTS PAGE Introduction PAGE 13 External characters Body wall Parenchyma Excretory system Male sexual organs Female sexual organs 20 Bibliography 25 Explanation of plates 28 11 Digestive system 16 Introduction species of appencliculate distome was first described by Rudolplii ('02 pp 76-78) as Fasciola crenata, and later ("09, pp 404, 405, tub 5, This fig I.) as Distoma creuatum It has since been included under Dis- tomum(or Apoblema) appendiculatum by Rudolphi (19), Monticelli ('91), Milhliug ('98), and also under Distomuin ventricosum by Wageuer ('60) It is described as Distomum ocreatum by Olsson ('67), and Linton (:00), as Apoblema ocreatum by Juel ('89), and as Hemiurus ocreatus by Looss (99) The name Hemiurus crenatus was first a^^plied to it by Liihe ( 01), who gives its synonomy and a brief characterization of the species The genus Hemiurus was established by Looss (99), who includes under it all appendiculate distomes except those lacking au Luhe proposes to raise appendix or having an extremely small one : the genus to the rank of a family, under which he would include twelve He describes three species belonging to Hemiurus s.str and genera mentions two others which are perhaps also to be included in the genus It is very doubtful Hemiurus crenatus, if the specimen shown in Olsson's Figure 98 is the ventral sucker is represented as twice since as large as the oral sucker, while in all the specimens I have examined Figure 19 very nearly equal five times four or the as is (Plate 35) pars prostatica represented being as long as it is in I think it probable I and have studied, any specimens the suckers are VOL XLV — KO in 1 size In Linton's BULLETIN that : MUSEUM OF COMPARATIVE ZOOLOGY some of the specimens referred by him not belong to Distomum ocreatum to this species My studies have been made on specimens taken from the stomacli of both Anguilla chrysypa Raf.^ and Osmerus mordax Mitchill during the mouths of October and November The parasite is by no means common, as I have frequently examined fifty or more stomaclis without finding a single specimen When present, the number found in a single host In December I obtained very varied from one to fifteen or twenty few specimens, and after that did not succeed in finding any, althougli I repeatedly examined stomachs of the infected species until about the middle of May Hot corrosive sublimate was found to give the best results as a fixing agent for specimens to be sectioned, tiiough as a fixative for specimens to be mounted it was not at all satisfactory For the latter purpose entire Alum Kleinenberg's picro-sulphuric mixture gaveT the best results carmine and Brazilin proved most satisfactory for staining sections and Delafield's haematoxylin for entire preparations carried on under the direction of Professor Mark, to for many suggestions and much The work whom I am has been indebted valuable assistance External Characters Upon measuring seven preserved specimens with the appendix extended was found that the average length was 2.6 mm., the (compare Fig 1), extremes being 1.71 mm and 3.219 mm The average width was 0.323 mm., the extremes being 0.222 mm and 0.444 mm Tiie average it length of the trunk was 1.982 mm and that of the appendix 0.799 mm., the appendix being therefore a little more than three-eigliths as long as the trunk Llihe (: 01) states that the appendix reaches about threefourths the length of the trunk The ventral and oral suckers are very nearly equal in size measurements made on From was found that the average diameter of the oral sucker was 0.224 mm., while that of the ventral sucker was 0.2G46 mm., though in some cases the oral sucker is equal in size to the ventral or five specimens, even a little it larger The oral sucker is at the anterior end and faces antero-ventrally From measurements on the five it was found that the distance of the centre of the ventral specimens, sucker from the anterior end of the body was from one-fourth to oneseventh of the entire length of the worm The genital pore lies ventral Rafinesque ('17) spelled this name chrisypa lander: anatomy of hemiurcs crenatus to the posterior suckers, or a end of the pharynx, about midway between the two little nearer the oral sucker Slightly in front of the ven- a deep, transverse, slit-like depression, which may be tral sucker The width of the fossa is slightly the as designated preacetabular fossa characteristic feature of this, as less than that of the ventral sucker is A well as of several other species of the Hemiuridae, is the ringed appearThe length of these rings varies according to the ance of the trunk state of contraction of the body, those near the posterior end of the trunk In the anterior end being, however, several times as long as those near The appendix is not one specimen 142 of these rings were counted but usually presents one or two slight constrictions rino^ed, Body Wall The wall of the body exhibits the usual structures: viz a cuticula, or external structureless covering, a layer of circular muscle fibres, a layer of and a layer of diagonal muscle fibres longitudinal muscle fibres, An inner and an outer layer of the cuticula, commonly described, are The rings noticed on the surface not distinguishable in this species The of the body are due to variation in the thickness of the cuticula end of a ring is about S.Qfx, whereas at the posterior end of the ring it is from two to four times as great in profile a notch marks the posterior (Plate 1, Fig 5), so that when seen thickness at the anterior end of each ring The outer (circular) layer of muscles of the body wall consists of very in transverse fibres small (about 0.5 /xin diameter) so closely set that sections they appear to form a continuous sheet and in longitudinal row of minute dots They are best seen in tangential sections sections a (Plate 3, Fig 34) The longitudinal fibres are much larger, measuring /x to /a in diameter They are circular or oval in cross section, and in good preparations show a clear central area, surrounded by a more deeply staining highly refractive portion Trematode muscle (Juel, '89 ; Pratt, fibres "98) as have been described by several authors having a structure similar to this None of the muscle fibres of the body wall show any traces of nuclei The layer of diagonal muscle fibres is quite well developed In transverse sections the diagonal fibres are not easily distinguished, but their and arrangement are well shown in tangential sections (Plate 3, Fig 34) They are slightly larger than the longitudinal fibres There are size BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY two series of fibres, The which cross each other at nearly right angles is such that the meshes are from two to four distance between the fibres Fibres of times as wide as the fibres all three layers are occasionally seen to branch In the appendix the body muscles are less strongly developed than find, as in the trunk, and the oblique muscle fibres are lacking and by Juel ('89), that the relative positions of the circular in the found those reverse of the fibres are muscle trunk, lonofitudinal stated the longitudinal fibres of the appendix being next to the cuticula (Plate 2, Juel calls attention to the agreement in position between the Fig 14) muscles of the appendix and those of the excretory vessel, and suggests that the muscles of the two have developed in connection with each other I think his suggestion quite pertinent and believe that the inversion of the muscle layers of the appendix is significant as to the method in which Pratt ('98) believes that the appendix is the the appendix originated la whole, or a part, of the excretory vesicle in an evaginated state young specimens of Apoblema [Ilemiurus] appendiculatum which are as end of the body what yet without an appendix he finds at the posterior an appendicular vesicle, a sack lined with a high columnar At its posterior end, this sack opens to the exterior by a epithelium he calls pore guarded by a sphincter, while into its anterior end the excretory Later this appendicular vesicle becomes evaginated to vesicle opens form the appendix and its epithelium is sooner or later shed In Hemiurus crenatus and other appendiculate distomes, so far as they in this particular, the excretory vesicle is provided with longitudinal muscle fibres which lie next to its structureless lining, and surrounding these are circular muscle fibres Upon evagination of have been described excretory vesicle the muscles of its wall would appear as body muscles, the outer layer consisting of longitudinal fibres and the inner found in the layer of circular fibres, which is precisely the condition the It appendix, but the reverse of that found in the rest of the body seems to me, therefore, that Pratt's view as to the origin of the appendix furnishes a satisfactory explanation of the difference between the arrangement of the muscle layers of the appendix and those of the trunk, — a condition difficult to offer any other explanation suckers are well developed, and both the radial and peripheral fibres show a clear central area, while the peripheSide views of fibres ral portion of the fibre shows a fibrillar structure The muscle for which it seems fibres of the clearly a longitudinal striation, and in cross section the peripheral portion of each fibre has the appearance of minute dots show lander: anatomy of HExMIURUS crenatus The bj longitudinal muscle fibres of Ogmogaster have been described Jagerskiold ('91) as consisting of fibrilla;, while he describes the circular muscle fibres as showing a clear central area and a peripheral, same condition as that described above for highly refractive portion, the the longitudinal muscle fibres of Ilemiurus crenatus Walter ('93) describes both the dorso-ventral muscle fibres and the muscle fibres of the body wall as having a fibrillar structure According to Staflbrd's ('96) account the dorso-ventral muscles of Aspidogaster have a fibrillar structure, and also show in cross section a deeply staining peripheral portion surrounding a less dee|)ly staining core There is a special development of muscle fibres in connection with the preacetabular fossa between which fibres The greater 28) is The is structure consists of a mass of radially arranged found a finely granular substance (Plate 3, Fig, portion of the structure lies anterior to the fossa There in the case of the suckers, and many no internal limiting membrane, as of the fibres pass out some distance into the parenchyma Parenchyma The parenchyma presents three principal modifications, a periphlayer, a vesicular parenchyma, occupying most of the the organs, and a cellular sheath found around the between space intestinal coeca in the posterior portion of the body (Plate 2, Fig 25) eral granular The peripheral granular portion, or sub-cuticula, forms quite a distinct layer nest to the body muscles, and it fills in the spaces between It appears to be rather irregularly but finely granular, the muscle fibres and from one to three times as thick as the cuticula (Fig 25, pa'ench layer as a whole shows no evidence of cellular structure, but imbedded in it are numerous groups of nuclei, each group being is The gran.) surrounded by a circumscribed mass of protoplasm (Plate 2, Fig 25; Plate 3, Figs 29-31) In each of these clusters can be counted from one to ten nuclei, the larger groups being the more common In the majority of cases each group appears to constitute a syncytium, but in the protoplasm to each is distinctly divided into cells (Fig 31) many groups Corresponding group of nuclei there occurs a thickening of the peripheral granuwhich protrudes into the vesicular parenchyma Each nucleus lar layer, shows a large number of small deeply staining granules, which are especially abundant in the periphery, and usually one much larger chromatic mass, the diameter of which the nucleus may be The protoplasm surrounding one-fourth as great as that of the nuclei is sharply marked BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY b from the granular parenchyma in which it, is imbedded, and it appears most cases to be homogeneous, but in some groups it has a finely These groups of nuclei are quite uniformly disgranular appearance off in tributed in the j^eripheral granular layer over all the body, parts of and similar groups are also found between the muscle fibres of the pharynx and suckers and occasionally in the vesicular parenchyma, especially in the anterior jiortion of the body There are also found in the granular layer of parenchyma somewhat larger oval, pyriform, or spindled-shaped cells (Plate 1, Figs, 4, 7-13) These cells are much less numerous than the subcuticular cells, as a rule deeper than they do, and never occur in large groups, though sometimes two may lie close together (Fig 11) The protoplasm stains deeply with carmine and shows large, often flake-like granules The lie nuclei are large and clear save for the single nucleolus, which is generally oval in form and unusually large, its length being often nearly as great as the diameter of the nucleus The long spindle-shaped cells (Fig 4) are undoubtedly destined to become parenchyme muscle fibres, and the cells, which are usually the smaller ones, may be very well shorter regarded as earlier stages axis of these cells is in the formation of such fibres to is The long the surface of the body, as usually parallel often the case with the parenchyme muscle fibres A third kind of cell to be found in the granular layer is the giant " the so-called " grossen Zellen of German authors The cells in Hemiurus which I take to be giant cells resemble somewhat the granular cell, Their cytoplasm stains but slightly, and is usually continued into several processes (Plate 4, Figs 39-41) There is a great variation in the amount of cytoplasm around the nucleus, in some cells cells just described the cytoplasmic portion of the cell being very large, while in others it forms such a thin sheath around the nucleus as to be scarcely apparent According to the recent researches of Bettendorf ('97) these cells are to be regarded as myoblasts, lying, as a rule, at some distance from their differentiated contractile portions, with which they are connected by If we regard the giant cells as delicate, branching processes of the muscles of the wall and the granular cells as in myoblasts body of muscle into fibre, i e as myoblasts development process parenchyme numerous, of parenchyme muscle, it is not at all surprising to find a close resemblance between them It is to be noted, however, that the method of formation of the muscle fibres is quite different in the two cases In one the contractile elements body of the become cell lies external to differentiated in such a them ; manner that the there are usually several contrac- Smaixwooo — Maturation Hamiiiea PLATE in 11 All figures photographic reproductions of sections magnified 670 diameters, and reproduction reduced to about 450 diameters Fig 73 Propliase of second maturation figure Fig 74 ; longer or indirect process Cliro- mosomes surrounded by a nuclear membrane Aciiromatic figure surrounded by the medullary and cortical layers of the sphere Iron ha;matoxylin (Compare Plate 7, Fig 42.) Prophase, second maturation, longer process The achromatic figure is still enclosed two groups in the wall of tiie parent ccntrosonie (not in focus), each with nuclear Ciiromosomes membrane in Iron haema- toxyiin and Bordeaux red (Compare Plate 7, Fig 41.) of second maturation spindle focused at the level of deep (polarSame stage as that of Figure 73 cell) end of tlie spindle Fig 75 End view Fig 76 The Fig 77 The central spindle between the two asters has almost disappeared it is Iron hu;matoxylin and represented by a wavy deeply staining band ; Bordeaux red (Compare Plate 7, Fig 46.) vesicular nucleus, containing the chromosomes, lies midway between the two asters, but the second maturation spindle has not been formed Brazilin (Compare Plate 7, Fig 47.) Fig 78 Polar view of the deep centrosome of second maturation figure stage as that of Figure 73 (Compare Plate 7, Fig 38.) Fig 79 Same membrane has disappeared, leaving the chromosomes free in cytoplasm, the granules of which are arranged into rows Fine fibres have grown out from the chromosomes a short distance toward The nuclear tiie the poles Brazilin (Compare Plate 7, Fig 49.) Fig 80 Metapiiase second maturation, longer or indirect process pare Plate 8, Fig 55.) Brazilin (Com- Smallwood.-Maturation H amine a '4 Plate 11 "J^J^^F 77 >t