A Study of One of the Distomes. 89 



pushed down again. Although watched for some hours it did 

 not get past the pharynx, neither did it appear to suffer any 

 change. 



The small body (/) situated immediately in front of the 

 posterior sucker is the opening of the reproductive organs. 

 It communicates with a long, tortuous tube (A'), strongly colored 

 and filled with ova. This is the greatly elongated uterus. 

 The whole of the body posterior to the acetabulum is occu- 

 pied by this long uterus, which is filled with thousands of 

 ova in various stages of development, purposely omitted in 

 the drawing that other parts may appear the more dis- 

 tinct. With this exception, the drawings represent the object 

 as actually seen. 



Our investigations lead lis to conclude that the uterus is 

 lined with epithelium of the ciliated variety. 



Directly behind the acetabulum are two bodies, the testes 

 (Z). Still more posteriorly, on the median line, is a large, 

 irregular body — the ovary (J/) — and passing off from either 

 side a narrow, slender tube, seen in this case only at the left side 

 {N'). These tubes connect the ovary with a long, glandular 

 mass, situated at either side of the body. These are the 

 yolk-forming glands (6>), seen well in this specimen. 



Owing to the great number of ova, the one on the opposite 

 side was hidden from view. Lastly we have the true excre- 

 tory and water-vascular system {P). This is composed of 

 two long, slender tubes, which coalesce in the median line to 

 form the sigmoidal duct (0, which suddenly enlarges to form 

 the contractile vesicle {R). We see that one of these tubes 

 crossing the acetabulum turns back upon itself just behind 

 the anterior sucker and terminates in a small indefinite point. 



The little projection (6") from the cephalic sucker has all 

 the appearance of being an organ of prehension, serving the 

 same purpose to this animal that the tongue does to the frog. 

 Such, however, is not the case, for it is used as a lancet to 

 pierce the parenchyma of the animal it infests, and thus open 

 a passage for the whole body to enter. If our distome is 

 slightly compressed, or in any way made uncomfortable, this 

 organ is thrust out suddenly at about the distance repre- 

 sented in the cut, to be as suddenly withdrawn, over and over 

 again. A careful examination reveals the fact that this lance 

 does not come from the mouth, but from the dorsal surface 



