FIG. 75. 



Lankesterella ranarum (Lank.) (par. Rana esculenta), phases of the life-history, a-/, schizogony. 

 a, 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. , the 

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

 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 microgainete ( g.) is separated off, and another 

 is forming at +. j-m, maturation of the macrogamete. j, full-grown macrogametocyte. t, the 

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

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

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

 macrogairete. n-p, sporogony. n, a zygote, still motile, with fragmented imcleus. 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 



