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masses are really sporoblasts, and they sooir secrete a covering of 
sporocyst. Within the sporocyst nuclear multiplication again takes 
place, till there are produced about sixteen nuclei in each (PI. XVI, 
fig. 1). The nuclei then range themselves in groups, eight at each pole. 
By a process of growing out from the protoplasmic mass there ai’e formed 
from each end eight sporozoites (PL XVI, fig. 7). A part of the proto¬ 
plasm remains as a residual body. In this manner there are produced 
large oocysts of about 100 /r in greatest length containing from thirty 
to fifty sporocysts of about 15 yU.-16 in length, and in each sporo¬ 
cyst sixteen sporozoites of about 14/r in length (PI. XVI, fig. 16). 
The sporozoites (PI. XVI, fig. 12) have been described by Christophers. 
They are elongate bodies of 14ya-15/u. in length and are packed tightly 
together within the sporocyst. The nuclei of the sporozoites resemble 
those of other stages of the haemogregarine. There is a mass of 
chromatin granules closely bound together. I have not been able to 
determine if a nuclear membrane or karyosome exists in this stage, but 
as the earlie.st forms found in the splenic cells have nuclei of this type, 
I do not doubt that the sporozoites have also. 
The presence of these large oocysts was not noticed by Christophers, 
probably owing to his method of studying the development. In making 
smears of the contents of ticks these large oocysts would certainly be 
ruptured and the sporocysts liberated. In sections the general arrange¬ 
ment of the various parts is much better retained. The production of 
the oocysts and sporocysts corresponds in almost every detail with the 
development given by Miller for the very similar haemogregarine of the 
rat. The average number of sporozoites in each case is sixteen. The 
number of sporozoites in each sporocyst in the case of Haemogregarina 
stepanowi and Haemogregarina nicoriae is only eight. 
The next stage in the development of the large oocysts in the dog 
tick is the dissolution of the cyst wall and the liberation of the 
sporocysts which wander about amongst the body contents of the ticks. 
Liberated sporocysts may be found in any part of the body outside the 
gut. In sections of ticks at this stage it is possible to find sporocysts 
in almost every section. The further development has not yet been 
traced. I have not been able to detect free sporozoites either in the 
body cavity or in the gut. In the case of the Haemogregarina stepanowi 
and in Haemogregarina nicoriae Reichenow and Robertson have 
described the liberation of the sporozoites from the sporocysts and their 
passage back into the cavity of the gut, whence undoubtedly they again 
enter the body of the tortoise. Christophers describes free sporozoites 
