W. S. Patton 151 
not hesitate to predict the method of sexual reproduction of all the 
haemogregarines. 
When criticising my remarks on L. leporis in the tick H. flava 
Dr Sambon refers to Miller’s (1909) recent paper on Leucocytozoon 
( Hepatozoon) perniciosum, and states that Miller has proved, “ that the 
sporogony of this species occurs in a rat mite, Lelaps echidninus,” and 
that Miller’s investigations have “ proved the correctness of the account 
I gave of the haemogregarines in my classification of the Haemoprotozoa 
which Sir Patrick Manson did me the honour of adopting and supporting 
in the fourth edition of his Manual of Tropical Diseases .” Here we 
have it that in 1907 Dr Sambon prophetically predicted the probable 
method of sporogony of the haemogregarines, and that now Miller’s 
work—though as yet unconfirmed—has proved the accuracy of Dr 
Sambon’s prediction. This is however regardless of the fact that at 
the time Dr Sambon classified the haemoprotozoa, he had in my opinion 
no grounds whatever for saying that the haemogregarine ookinete 
encysts and produces sporozoites in secondary cysts or sporebags. This, 
I suppose, is what Dr Sambon calls “ dabbling in zoological matters.” 
Miller summarises the sexual cycle of L. perniciosum as follows: 
“ When the blood of an infected rat is swallowed by a mite the encysted 
trophozoits are set free in the stomach by solution of the cyst as free 
vermicules. Two similar vermicules become associated and conjugate. 
One, the macrogamete, grows larger and partly surrounds the other, the 
microgamete. The protoplasm becomes fused and later the nuclei 
conjugate and fuse to form a zygote. The zygote becomes a sluggishly 
motile ookinet, which penetrates the stomach wall of the mite and 
enters the body tissues and becomes encysted (oocyst). Here a re¬ 
markable enlargement of the karyosome takes place. The parasite 
increases enormously in size. The nucleus of the spherical sporont 
thus formed undergoes division into many daughter nuclei, which 
migrate to the surface of the sporont. The surface of the latter 
becomes mammillated. The projections, each of which contains a 
nucleus, increase in size and length; later they are broken off and 
each becomes a sporoblast. The nucleus of the sporoblast undergoes 
division, the resulting nuclei being arranged at the poles. The sporo¬ 
blast increases in size and a cyst wall developes. Around each nucleus 
a sporozoite is formed. In the ripe sporocyst, which measures 25 by 30 
micra, the sporozoites, 16 in number (average) are arranged at the poles. 
The large cyst (oocyst) contains from 50 to 100 of such sporocysts. 
When the mite is swallowed by a rat the cycle is repeated.” 
