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Oriental Sore 
surrounding tissue. Robertson has also described a similar method of 
conjugation in the case of another baemogregarine H. nicoriae. The 
sexual process for the dog haemogregarlne was described by Christophers, 
but Reiclienow is of the opinion that here also the conjugation will 
ultimately be found to be of the Adelea type. 
Miller, however, has described for the rat haemogregarine a complete 
conjugation of two unaltered haemogregarines in the gut of the mite 
Letups echidninus. It is possible that here the conjugation will be 
found also to be on the lines of that of Adelea ovata. Further work 
alone will settle the question of the exact details of the conjugation of 
these leucocytic haemogregarines of the dog and rat. 
I have mentioned that I was able to trace the haemogregarines 
through the epithelium of the gut into the tissues of the body of the 
tick, but the forms I have seen might have been ookinetes passing 
through the gut wall after conjugation as do the ookinetes of the rat 
haemogregarine according to Miller, or they may have been even the 
sporozoites resulting from a sporozony undetected by me in the gut of 
the tick, as described by Pteichenow and Robertson. 
In order to follow in detail the stages which occur after the 
haemogregarines have reached the body tissues of the tick, one must 
have recourse to artificial infections. The ticks with which I conducted 
these investigations were taken from naturally infected dogs in which 
the infection was never laige enough to enable me to follow in detail 
the next few stages. It is sometimes very difficult to distinguish the 
very young oocysts from the tissue cells of the ticks. 
The next stage which I have been able to distinguish clearly is 
shown at PI. XVI, fig. 11. Here it will be seen that a large cell has 
been produced, that nuclear multiplication has taken place, till there 
are present about thirty nuclei. I am not quite clear whether this is a 
growing oocyst or whether it is some stage in the production of gametes 
as described by Christophers. Miller has described for the rat haemo¬ 
gregarine an enormous increase in size of the oocyst. A similar 
increase in size takes place in the case of the dog haemogregarine. 
Eventually large oocysts of about 100 jx in greatest diameter are 
produced. These are found in the sections to lie outside the gut wall 
embedded in the surrounding tissues. These oocysts contain at first a 
single mass of protoplasm with thirty to fifty nuclei. By a process of 
budding (PI. XVI, fig. 17) there are separated off protoplasmic masses 
each with a single nucleus. A great part of the protoplasm is unused 
in this process and is left over as a residual body. The protoplasmic 
