152 Haemogregarines 
This account of the sexual cycle of the parasite at once recalls the 
appearances I have seen in P or ocephalus pattoni from the lung of Zamenis 
mucosus, and are also very similar to those described by Christophers 
(1905) from the body cavity of Haematopinus stephensi from Gerbillus 
indicus. Not only are the ripe cysts in each case almost identical in 
that they contain small cysts full of sausage-shaped bodies, but the 
earlier stages I have seen in the linguatulid and those described by 
Christophers from the louse are very striking in their similarity. 
I have no doubt therefore that the parasites I have seen in P. pattoni, 
and those described by Christophers from the louse, and by Miller in 
the mite, represent stages in the development of different species of the 
same genus of a sporozoon. If we are to accept Miller’s work as correct 
it follows that the parasites (cysts) seen by Prowazek, Sambon and 
myself in linguatulids represent the various stages in the sexual cycle of 
the haemogregarines of Python reticulatus, Lachesis mutus and Zamenis 
mucosus. The question then arises how are the sporozoites of these 
haemogregarines transmitted from an infected to an uninfected snake ? 
According to Miller’s conclusions it would be necessary for the uninfected 
snakes to swallow the infected linguatulids. It is not definitely known 
how snakes become infected with these arthropods, but it is believed 
they swallow their eggs or immature stages in their food ; for instance 
the rat snake, Zamenis mucosus, probably swallows the eggs of P. pattoni 
in the frogs and toads, which are its principal food. At any rate it is 
well established that snakes harbour the adult stages of linguatulids, 
and are the definitive hosts of these arthropods. It is therefore most 
improbable that snakes swallow adult linguatulids, and if this is true, it 
is impossible at present to understand how snakes harbouring linguatulids 
can become iufected with the sporozoites of haemogregarines in these 
arthropods. If it is impossible to understand how this method of 
infection can take place, it is equally as difficult to understand how an 
uninfected snake could become infected by the bite of an adult (haemo- 
gregarine-infected) linguatulid. Realising these difficulties in 1905, 
when I first found the cysts in P. pattoni, I came to the conclusion that 
these parasites did not represent stages in the sexual cycle of a 
haemogregarine. I have examined over 60 specimens of this lingua¬ 
tulid and could trace no connection between the haemogregarine of 
Zamenis mucosus and the parasites in P. 'pattoni. With regard to the 
cysts Prowazek (1908) has recently found in P. moniliformis, I pointed 
out that he suggests that they may represent a further development of 
Id. pythonis ; Dr Sambon however speaks of “ Prowazek’s discovery of 
