OUR DOMESTICATED ANIMALS. 



15 



To illustrate the leading characteristics of fluke de- 

 velopment, nothing can be better than a few good figures 

 of amphistomatous larvas. Here are some carefully selected 

 and much reduced in size, from Dr. Pagenstecher's admi- 

 rable representations of trematode larvae (Fig. 5). The 

 larger larval form, A, represents what is termed a sporo- 

 cyst, and through its transparent skin we may readily 

 recognise the bulb of the oesophagus, a, leading to a 

 globular and rudimentary stomach, marked b. In addi- 

 tion to the digestive organs, we may notice in the interior 

 a variable number of loosely floating bodies, c ; these 



Fig. 5. Larval Amfhistomes. 



latter being internal buds, so to speak, destined to be 

 transformed into perfect cercarias. 



The somewhat more highly organised larva or Cercarea, 

 B, exhibits a pair of eyes, d 3 a ventral sucker, e, and a 

 conspicuous tail, /; and when the same microscopic crea- 

 ture is viewed laterally, as at 0, we observe an additional 

 cavity, g. By the dislocation of the tail, which is even- 

 tually thrown off, as seen in the cercarean form marked 

 D, this hollow space, h 3 imparts a truncate figure to the 

 animalcule. A cercarea in this unhappy-looking, tailless 



