Natural History of Entozoa. 



195 



previously encysted itself. The drawing represents the escape 

 from the cyst.* Fig. 9 represents the young Distoma militare 

 in a sexually immature state. With the help of previous 

 descriptions the several parts will be easily recognized. Greater 

 complications than those we have mentioned occur in the 

 reproduction and development of these worms ; but for full 

 details we must refer to Dr. Cobbold's work. 



Fig. 9. 



According to Pagenstecher — as cited by Cobbold — the eggs 

 of the Trematoda, to which the flukes belong, vary in size, form, 

 and colour. When mature they contain a ciliated or non- 

 ciliated embryo. These eggs are, by various means, conveyed 

 to the bodies of mollusks, and the germs they contain are 

 developed into what are called " nurses," some of which are 

 more highly organized than others. These nurses produce 

 offspring of the bud sort. " Tailed trematode larvse (cercarix), 



* a Month, i cephalic sucker, c pharyngeal bulb, d oesophagus, e e digestive 

 cceca, f coronal spines, g contractile vesicle, h water vascular vessels, i i yelk- 

 forming glands, Tc I cellules from which other reproductive organs will grow. 



VOL. VI. — NO. Ill, 



