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CONDITIONS INFLUENCING THE TRANSMISSION 
OF EAST COAST FEVERi. 
By GEORGE H. F. NUTTALL, M.A., M.D., Ph.])., Sc.D., F.R.S., 
Quick Professor of Biology in the University of Cambridge, 
AND EDWARD HINDLE, B.A., Ph.D, F.L.S., 
Late Beit Memorial Besearch Felloiv; Assistant to the Quick 
Professor of Biology, Cambridge. 
{From the Quick Laboratory, University of Cambridge.) 
In spite of mimerous researches the life-cycle of Theileria parva, the 
parasite of East Coast Fever, has not yet been elucidated. Especially 
is this the case with regard to the life-cycle of the parasite within the 
invertebrate host, Rhiincephalus appendiculatus, for the only account 
hitherto published, namely that of Gonder (1911), is very incomplete 
and has not been confirmed. Accordingly, we have performed various 
experiments and examined the organs of numerous ticks in the attempt 
to throw some light on the subject, and, if possible, confirm Gonder’s 
account of the life-cycle of Theileria parva within the invertebrate host. 
Although we have examined both smears and sections made from all 
parts of the bodies of more than twenty infected ticks, we have not been 
able to detect any appearances w'hich could not be found in normal 
ticks, when the tissues of both the infected and clean ticks were 
searched with equal diligence. Considering that practically 100 “/o of 
the ticks which imbibe the parasites are provedly infective, the number 
we examined should have sufficed for their detection. Our attempts to 
1 The expenses in connection with this investigation are being defrayed by the aid of 
a grant from the Rockefeller Institute for Medical Research. 
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