158 :^. GOJO. 



I. The Epidermis. 



The nature of the integument of the Trematodes has been 

 variously represented by various authors. This subject I hope to 

 discuss more fully in a later work which shall treat of our ecto- 

 parasitic Trematodes in general. Zeller'^ tells us that if no occa- 

 sion is offered the embryos to attach themselves to the gill, " schon 

 nach Verfluss von 5 Stunden (^ after the embryos have left the e^^g) 

 einzelne der Wimperzellen reissen sich los, bald mehrere und schliess- 

 lich alle, ilinmiern aber auch abgetrennt noch eine Zeit lang fort." 

 The embryos finally die. It is not clear from his statements 

 whether this throwing off of the " Wimperzellen " is a normal process 

 or not. In Polijstomum he merely says that they " schrumpfen," but 

 does not describe their exact fate. In the case of Distomum, how- 

 ever, it has been proved by Schwarze^^ and Biehringer^^ that the 

 so-called " cuticula '" consists originally of cells which undergo one 

 by one a peculiar transformation, and which do not at any time possess 

 the typical ej)ithelial arrangement. After the first rough manuscript 

 of these pages had been finished, I received the article of Braun''* in 

 " Centrbl. für Bakteriologie u. Parasitenkande," in which the writer 

 brino-s forward some strong and interesting evidences as to the 

 epidermal nature of the integument. In view of these facts estab- 

 lished by the preceding investigators, I believe I may regard the 

 inteo-ument of the monogenetic Trematodes as a modified epidermis, — 

 the more so from the consideration that it has a distinct cuticle and 



1) Zeller— 1. c. p. 173. 



2) Schwarze — Die posi^embryouale Entwiekhmo- <lei- Treinntoden. Ztschr. f. w. Zool. Bd. 

 XLII. 188G. p. 49. 



3) Bielu'inoer — Beitrüge zur Anatomie n. Entwickl.-gesciiichte d. Trematoden. Arljeiten 

 a. d. zool.-zoot. Inst, in Würzbnrg. Bd. VIT. 18S5. p. 4. 



4) Braun, Max — Einige Bemerkungen ü. d. Körperbedeckung ectoparasiti scher Tremato- 

 çlen. Centralbl, f. Bakteriol. u. Parasitenkunde. Bd. VII. 1890. p. 594 (Nr. 19.) 



