Febeuaby 17, 1911] 



SGimCE 



269 



racy. Furthermore, the papers of King on Bufo 

 lentiginosus and of Kusehakewitch on Bana escu- 

 lenta have confirmed my work on Bana pipiens. 

 While Dustin strikes a discordant note in his 

 account of the origin of the sex-cells of Bana 

 fusca and Bufo vulgaris, it may not be wide of 

 the mark to tentatively advance the view that the 

 sex-cells arise in the Urodeles from that portion 

 of the mesoderm between the anlage of the meso- 

 blastic somites and lateral plate, while in the 

 Anurans they arise from that part of the endo- 

 derm that forms the median portion of the roof 

 of the arehenteron. This is not inconsistent with 

 the conception of the sex-cells which is being more 

 and more firmly established, namely, that they 

 are cells preserved from early stages in an undif- 

 ferentiated condition and that they are capable of 

 considerable migration along radically difl'erent 

 paths. There must, as a matter of course, be a 

 more or less close correspondence in these migra- 

 tion paths in closely allied forms, but radical 

 differences might be expected in such funda- 

 mentally different groups as the Urodeles and the 

 Anurans. 



Anatomical Illustration before Vesalius (with il- 

 lustrations from original sources) : W. A. LoCT, 

 Northwestern University. 

 On the Distribution in the United States and 

 some Points in the Habits of Clinostomum, 

 margiimtum: Henet Leslie Osbobn, Hamline 

 University. 



This trematode was first recorded in Europe 

 by Rudolphi in 1809 under the name Distomum 

 marginatum. The following summary shows the 

 records of its occurrence in this country with 

 date, writer, name, host and infected part, and 

 locality: 1856, Leidy, Clinostomum gradle, Esox, 

 intestine, Delaware River; 1877, Leidy, Distomum 

 galaotosomum, Boccus lineatus, Philadelphia; 

 1879, Wright, Distomum gradle, Peroa flaves- 

 ceres, branchiostegal membranes, Toronto; 1879, 

 Wright, Distomum heterostomum, Botaurus 

 minor, mouth, Toronto; 1885, Looss, Distomum 

 reticulatum, silurid fish encysted in muscle tissue, 

 Porto Rico; 1895, MaeCallum, Distomum, gradle, 

 frog, encysted in pectoral muscle, Toronto; 1897, 

 MacCallum, Distomum heterostomum, Ardea 

 herodias, mouth, Toronto; 1898, Distomum gra- 

 dle, Eupomotis pallidus, pectoral fin and roof of 

 mouth, Kansas City, Mo.; 1901, Osborn, Clino- 

 stomum marginatum, Micropterus dolomieu, en- 

 cysted in muscle, Nebish, Mich.; 1901, Osborn, 

 Clinostomum marginatum, Ardea herodias, throat, 

 Nebish, Mich.; 1903, Clinostomum marginatum. 



Bana virescens, encysted in coelom wall and sub- 

 cutaneous lymph spaces, Saint Paul, Minn.; 1903, 

 Young, Clinostomum marginatum, Micropterus 

 dolomieu, encysted in branchiostegal membranes 

 and muscle, Troy, Ohio; 1904, Stafford, Clinosto- 

 mum gracile, Perca flavescetis, gills, Montreal. 

 Its distribution is thus shown to be very wide, as 

 indicated by the names Philadelphia, Troy 

 (Ohio), Kansas City, Saint Paul, Nebish, Toronto 

 and Montreal. And yet we do not know its pri- 

 mary host, the worm being virtually completely 

 developed when found in the fish and frog. It is a 

 trematode of economic importance, since it in- 

 fects the edible portion of one of our principal 

 game fishes, though it is presumably not strictly 

 harmful to man. It is evidently veiy widely 

 spread in northern and eastern United States and 

 may be expected to be found outside the limits 

 already noted as soon as search is made. The 

 habits of the worm were studied in the forms 

 encysted in the bass. The cyst is a perversion of 

 the endomysial connective tissue and is wholly 

 contributed by the host. The worm in the cyst 

 is bent twice on itself, the ventral surface being 

 turned toward the inner surface of the cyst 

 whose cavity is completely filled by the worm. 

 Immediately on escaping from the cyst the worm 

 is very active indeed, its movements, besides 

 many random and irregular ones, falling under 

 two types: a retraction of the anterior end, pro- 

 ducing a club-shaped front region possibly related 

 with adhesion, and a thinning and flattening of 

 the body such that its ventral surface becomes 

 somewhat concave and the margins of the body 

 assume the appearance of lateral fins. Neither 

 of these two body forms were made practical use 

 of by the worm, the body merely taking on the 

 shape momentarily and then relaxing back at 

 once into the resting form. 



The worms in the frog were studied at St. 

 Paul. They are not so much found in the muscle 

 of the frog, their usual location in the fish, as in 

 the ooelomic wall where the cysts lie, not in the 

 muscular tissue, but between it and the perito- 

 neum. The cysts, too, are very much larger than 

 those in the fish and the worm is bent double 

 within, the ventral surface being external. The 

 cysts are similar in structure to those in the fish, 

 being made up of fibrous tissue and supplied with 

 a distinct capillary network. 



It is planned to publish this paper in the 

 Biological Bulletin. 



The Transmission of Trypanosoma lewisi hy Bat 

 Fleas (Ceratophyllus sp. and Pulex sp.), with 



