Natural History of Entozoa. 



193 



given to the public, we find that "in the adult or sexually 

 mature condition the Distoma militare produces a limited 

 number of oval-shaped eggs (Fig. 5 a), which, after the usual 

 process of yelk segmentation, give birth to an oval, free- 

 swimming, and finely ciliated embryo (b), the latter subse- 

 quently developing in its interior an oblong organism called a 

 sporocyst (Scolex, Yan Beneden) . All the distomes commence 

 life in this manner, but Yan Beneden is not absolutely certain 

 that the ciliated embryos here drawn from his figures (b and c) 

 were produced by the ova of the particular distome now 

 employed for illustration.-" 



This does not matter for our present purpose, as the process 



Tio:. 5. 



Fig. 6. 



in all flukes is essentially the same, and the "sporocyst" at 

 the time of its separation from the ciliated embryo presents a 

 very simple appearance {d), showing a sort of head and body, 

 the latter containing a digestive tube or coecum in its interior. 

 There is likewise a slight fissuration of the caudal end, indi- 

 cating the first rudiments of two appendages, which, in a more 

 advanced condition of the sporocyst, look like a pair of 

 imperfectly fashioned limbs. ... In the next stage (Fig. 6 e), 

 we have a well developed head (a) and body (&), the tail (c) 

 becoming pointed and strongly pronounced. In these sketches 

 / represents an cesophagal bulb, g the stomach, and i imper- 

 fectly developed offspring called cercarice, which abound in the 

 interior of the sporocyst. 



