Fio. 75. 



1 Lankesteretta ronarwm(Lank.) (par. Rana esculenta), phases of the life-history, a-/, schizogony. 

 o, youngest stages of the parasite ; mz shows a free merozoite ; tr, tr, two young trophozoites 

 within a blood-corpuscle, with one and two chromatin bodies respectively. 6, a blood-corpuscle, 

 containing a full-grown trophozoite (schizont), with numerous chromatin bodies, preparing to 

 sporulate. c, the schizont is taking the form of -an U. d, The schizont has become spherical, 

 but still shows the line of suture between the two loops of the U in the last stage, e, the 

 schizont is a perfect sphere. /, the schizont is segmented up into a number of merozoites (m*) 

 round a mass of residual protoplasm (r.p). g-i, formation of microgametes. g, a full-grown 

 microgametocyte with minute chromatin corpuscles in the nucleus, h, the chromatin cor- 

 puscles are dispersed through the body, i, a microgamete ( <J g.) is separated off, and another 

 fa forming at +. j-m, maturation of the macrogamete. j, full-grown inacrogametocyte. k, the 

 nucleus of the macrogamete has undergone division into two. I, one of the nuclei (n') is degen- 

 erating, m, at the spot where the nucleus of the macrogamete underwent degeneration, s 

 microgamete ( <$) has attached itself, and from this spot a fine canal leads to the nucleus of the 

 macrogair.ete. n-p, sporogony. n, a zygote, still motile, .with fragmented nucleus, o, an 

 encysted zygote, or oocyst. p, a sporozoite. g-i and n are free in the blood-plasma, j-m are 

 in blood-corpuscles in the same way as a-/, o is encysted in an epithelial cell of the intestine. 

 N, nucleus of the blood-corpuscle ; n, of the parasite. (After Hintze.) Magnified 2250 diameters. 



260 



