X 68 ZOOLOGY FOR MEDICAL STUDENTS CHAP. 



continuing its life-history unless it encounters a water-snailusually one 



,us species of Isidora (= Bulinus). In the liver of the snail 



joma takes the form of a long more or less tubular sporo- 



.tnd the germ-cells in the interior of this, which were already 



FIG. 77. 



A, Ventral view of adult male with the female in position between the infolded 

 edges of its body ; B, eggs of (i) S. hacmatnbium, (2) S. mansoni and (3) S. japonicum C, mira- 

 c i' limn; D, sporocyst ; E, cercaria. B and C are more highly magnified than the other stages. 

 *x, Alimentary canal (vestigial) ; a.s, anterior sucker ; g, gland-cell ; g.c, germ-cells ; n, nephridium ; 

 n.g, nerve-ganglion ; v.s, ventral sucker. 



recognizable in the miracidium stage (Fig. 77, C ; g.c), develop into 



~, D and E) with forked tails. 



< T< -urine are not capable of remaining alive in the free state 



for more tliun about 40 hours, but if within this period they come in 



\\iih the warm skin of a mammalian host they cast off their tails 



