STUDIES ON THK ECTOPARASITIG TREMATODES OF JAPAN. g 3 



therefore perhaps allowable to believe that the pigment granules are 

 normally thrown out into the intestine and there furnish the necessary 

 means for the digestion of food. On the other .hand, this observation 

 may also be advanced in favour of the third view, according to which 

 the pigment granules would be finally thrown away by way of the 

 mouth. Zeller indeed says that the intestinal cells detach themselves 

 from the wall ; and in this case it is difficult to understand the total 

 absence of any phenomena of division among them. According to my 

 own observation, however, only the pigment granules seem to be 

 thrown out, surrounded by a scanty mass of protoplasm, while the 

 cells themselves in all probability remain collapsed in their former 

 positions, and again resume their activity after the lapse of a certain 

 interval. According to the second view, the smaller cells observed in 

 Onchocotyle with a well staining protoplasm and containing fewer 

 granules of smaller size are to be regarded as those which have not 

 yet arrived at the height of secretory activity ; while according to the 

 third view they are to be regarded as those in which much refuse 

 matter has not yet accumulated. 



If digestion be regarded as taking place in the cavity of the 

 intestine by means of the pigment granules acting as a ferment, then its 

 product could pass into the tissue only by osmosis and filtration. If, 

 on the other hand, the pigment granules be regarded, according to the 

 third view, as the indigestible remnants of the food taken in by the 

 cells, then digestion has to be regarded as taking place intracell- 

 ularly ; but in this case the essential nature of the process would 

 remain unknown ; and it remains, moreover, to ask in what way the 

 digested food is passed on into the fluid which fills the mesenchyma — 

 a fluid which furnishes in all probability the necessary nutriment to 

 the various organs. I feel myself therefore obliged to leave the nature 

 of the pigment granules undetermined. 



