628 



troduction of solid particles from the intestine, and that they do not 

 induce a floAv of fluid into the lumen as claimed. No experimental 

 evidence has yet been secured to substantiate this inferential view 

 but it seems plausible. For some reasons there is even a better basis 

 for ascribing this filtering function to the cilia of the chylus cells 

 than to those of the nephridia. In the first place, the canals of the 

 chylus cells end blindly, while the nephridial canals have external 

 openings and in consequence the nephridial lumen may sometimes 

 be almost or entirely empty, when, as claimed by Cuenot, it is possi- 

 ble for the cilia of the nephrostome to aid in the introduction of the 

 fluids. On the other hand, the chylus cells occur in a part of the 

 intestine where, under normal conditions, the nutritive fluid is con- 

 stantly present. Since the intracellular canal of each cell has but 

 one opening, the canal is presumably at all times filled with fluid, 

 the amount of which is far more dependent on pressure conditions 

 in neighboring parts than on any action of the cilia. The powerful 

 and frequently changing muscular contractions in various parts of 

 the body are accompanied by more or less violent disturbances of 

 pressure and consequent movements in the fluid contents. It seems 

 reasonable to assume that such disturbances would more profoundly 

 affect the extensive digestive tract and its contents than the diminu- 

 tive nephridium, which is to such a considerable extent freely 

 suspended in fluid. In the second place, the apical ends of the chylus 

 cells are exiposed to great quantities of solid particles, since the con- 

 tents of the digestive tract must pass by them, and yet none of the 

 preparations examined by us have shown any indication of the pres- 

 ence of such material in the canals. Unless there were some provi- 

 sions for the prevention of the entrance of solid matter these blind 

 canals would be almost sure to contain such material and their func- 

 tional efficiency be correspondingly reduced. 



MARIONINA Michaelsen 



During the autumn of 1895 a study of the animal life in the 

 waterworks reservoir of Urbana, Illinois, was made by Miss Bertha 

 V. H. Forbes, a student in the University of Illinois, and in her 

 collections were a moderate number of small enchytrseid worms. 

 They were turned over to the senior author of this paper and were 

 partly worked up at that time, but circumstances prevented the com- 

 pletion of the work, and nothing further was done with the worms 

 until the present year, when their further study was undertaken by 

 the junior author. They proved to be an undescribed species of 

 Marionina. 



