174 



s. GOTO. 



such HS we. niv wont to see in the Distoines. In its .stead, we find large 

 cells (Figs. 14, 16. 19, de) separatee] from one another by a considerable 

 interval, and filJed with duvk-I)rown or sometimes even black gra- 

 nnies. I have not (Jl)ser^•ed any wall or nncleus in these (.-ells, al- 

 though Zeller'' points to the presence oi" the latter in J'o/ystonium. and 

 I could distinctly oljserve it in OrtohotJiriiün. These black {»igment- 

 containin"' cells I hold, m agreement with Taschenbero','^ to be dio^estive 

 cells, and the pigment-grannies to be tood-particles taken in from the 

 ca\itv of the intestirje. Digestion, therefore, takes place in the allied 

 forms intracellulary, as in the Turljellarians. The intervals between 

 these cells are usually destitute of any distinct meud.u'ane in the 

 anterior half of the body, so that here the digestive svsteni consists 

 of mere hollows in the mesenchyma ; but in the p<.)sterior part, where 

 the intestine is simple, 1 could usually distinguish a more or less dis- 

 tinct memlirane of compact connective tissue. 



VI. The Excretory System. 



The excretor}'' system (jf the Plathelminthes has been minute- 

 ly examined by Fraipont,"' Lang," l-*intner''' R. AVright and 

 ^lacallum,''' and some others. ]>y these investigations two [)oints 

 seem to have been lirndy established : 1) That the excretory system 



1) Zeller — Untersuch, ü. d. Entwiek. n. d. Bau. d. Polystomum integerrimum. Ztschr. f. w. 

 Zool. Bd. XXir. 1872. p. 19. 



2) Taschenber;;- — Weitere Beiträi^e. [> 11. 



S) Fraipunt— itecherches sur l'appareil excréteur des 'l'réujatodt s. Archiv, d. Biologie. T. 

 I. I have not been able to gain access to this work, aud_ am indebted for its account to J. V 

 Carus's " Zoologischer Jahresbericht" (1880. 1. p. 277) and to Looss (1. c). 



4) Lang— Der Bau von Gunda segmentata u. d. Verwandtschaft etc. Mittheil. a. d. zool. 

 Station z. Xeapel. Bd. III. 1882. p. 187. 



5) Pintner -Untersuch, ü. d. Bau. d. Bandwurmkörpers, mit bes. Berücksichtigung etc. 

 Arb-it. a. d. zool.-zoot. Inst. d. Univ. Wien, etc. Bd. III. 1880. 2. Heft. 



C) R. Wright and Macallum— 1. c. p. 20. 



