214 HENRY LESLIE OSBORN 



tions after the application of iroii-haematoxylin, cilia are clearly 

 seen as sharp black wiry looking lines. 



In view of the fact that these ciliary organs produce strong 

 current which flows forward, we are compelled to suppose that 

 the recurrent vessel discharges directly into the collecting vessel, 

 although as already noted it has not been possible to recognize 

 the connection. 



Flame-cells and capillaries. The ultimate members of the ex- 

 cretory apparatus of Clinostomum are very imperfectly known 

 as yet. Much attention and time have been dedicated to the 

 effort to trace these parts in the living animal with very inade- 

 quate reward. Some glimpses of them have been obtained how- 

 ever both in life and in sectioned material. Flame-cells have been 

 seen; they are very tall and slender with a narrow base where the 

 elongate and narrow mass of cilia are attached. A detailed 

 account, with illustration of these flame-cells together with some 

 other finer points, must be reserved for a later article. 



It has not been possible to determine the mode of arrangement 

 of the capillaries and connecting vessels. In some places the 

 capillaries have been recognized. They ran in a posterior direc- 

 tion. Vibrating ciliary organs could be seen within them. It 

 was not possible in any case to trace these vessels to a point of 

 connection with the recurrent vessel and I feel very strongly 

 convinced that the recurrent vessel does not receive any branches. 



EXCRETORY SYSTEM IN TREMATODES IN GENERAL 



There is considerable difference in the plan of anatomical organ- 

 ization of the excretory systems of different trematodes. In all 

 there is a system of flame-cells and their capillaries and one, or 

 occasionally two (e.g., Aspidogaster), posteriorly located excre- 

 tory pores. But there is great difference as to the vessels lying 

 between the external pore and the capillaries. All degrees of 

 distance between the terminal bladder and the capillaries can 

 be found. In Opisthoglyphe endolobum (Looss, '94, fig. 157) a 

 large forked chamber, confined to the posterior third of the body, 

 receives directly a vessel formed by the junction of the capil- 



