1919] Coi't: Eggs and Miracidia of Human Schistosomes 



513 



standard textbooks, since they give an entirely erroneous picture of 

 the structure of the miracidium of 8. mansom. 



I was unable to trace completely the connections of the tubules of 

 the excretory system in this miracidium. The excretory pores (fig. 2, 

 exp) are located on each side of the body near the posterior end. 



Fig. 4. Miracidium of S. mansoni within the egg, lateral view; letters as 

 in figure 2; also vm, vitelline membrane. 



Four large flame cells (fig. 4, /) are present, draining the anterior and 

 posterior regions on each side. The individual flame cell is very 

 large in proportion to the size of the miracidium, having a length 

 of about one-third the width of its body. The flame cells in the 

 miracidium of Schistosoma mansoni differ in position from those of 

 the miracidia of S. haematobium and S. japonicum, since they lie 

 almost perpendicular to the long axis (cf. figs. 4, /; 6, /). For this 



