W. S. Patton 
319 
opportunity of studying no less than five haemogregarines in Rana 
tigrina and Rana hexydactyla, not only in the frogs but in the leech 
which transmits them. I have also studied the haemogregarine of 
Emyda granosa both in the tortoise and in the transmitting leech. 
Lastly, I have had the unique opportunity of studying three mam¬ 
malian Leucocytozoa : L. funambuli, L. felis domestici and L. leporis. 
With this large material at my disposal I have made an exhaustive 
effort to trace out the extracorporeal life histories of these intracellular 
parasites of mammals and reptiles, but in every case I have failed to 
find any developmental cycle in the corresponding blood-sucking 
invertebrates. In the case of the leech from Emyda granosa, Christo¬ 
phers once showed me some bodies which suggested developmental 
forms of the haemogregarine of the tortoise; I have examined these 
parasites in the leech, but can only come to the conclusion that they 
probably represent some stage in the life cycle of a Coccidium parasitic 
in the leech. 
A few observations on L. leporis in the tick Haemaphysalis flava 
have suggested to me that the method of transmission of these parasites 
will eventually prove to be mechanical and that the characteristic 
vermicules,— whose sex, by the way, I am at present unable to determine ,— 
free themselves in the intestinal tracts of the various invertebrate hosts 
and in some manner at present unknown make their way back to the 
biting parts. I have actual experimental evidence proving that the 
vermicules of L. leporis can remain alive in the alimentary tract of 
larvae and nymphs of H. flava for at least 15 days. 
I am at a loss, therefore, to understand how Sambon and Seligmann 
have been able to observe adult sporonts, schizonts, etc., and how they 
are in a position to state these parasites have a sporogonic cycle in 
invertebrate hosts. It remains to be seen what observations they have 
made on the curious cycle found in the lungs and liver of snakes 
infected with haemogregarines. I have examined many examples of all 
the stages of this cycle not only in the stained condition but par¬ 
ticularly in the fresh condition (for 12 hours) in the lung of Zamenis 
mucosus , and I have not been able to satisfy myself as to whether this 
cycle of multiplication is an asexual or sexual process; for this reason 
I could not definitely say what the different forms seen in the peripheral 
blood of all my snakes really represented. Yet I find Sambon and 
Seligmann call some of these merozoites, others adult schizonts, sporonts, 
etc. As far as I can gather they have principally studied these parasites 
in the peripheral blood of snakes, so that I cannot see their grounds 
