G. H. F. Nuttall, H. B. Fantham and A. Porter 327 
describe and figure (iv. 1907, p. 232). These characters suffice to 
distinguish the genus Piroplasma without entering into further details 
regarding the nuclear structure or mode of multiplication in the 
circulating blood. This process of multiplication has been observed 
repeatedly in P. cam's (Nuttall and Graham-Smith, 1907) and P. bovis 
(Nuttall, 1909, see this volume, p. 341), in living parasites, and corre¬ 
sponding “budding” forms were detected in stained films of the three 
species of Piroplasma named. 
Theiler (1904) was the first to demonstrate that T.parva is conveyed 
by ticks. He found that Rhipicephalus appendiculatus and Rh. simus 
were both capable of conveying East Coast Fever to healthy cattle. 
Rhipicephalus appendiculatus, having sucked infected blood as a larva is 
infective as a nymph, or having sucked infected blood as a nymph is 
infective in the adult stage. Rh. simus, infected as a larva, proved 
infective in the next or nymphal stage. Lounsbury (1906, p. 643) has 
found the adult infective. Theiler regards Rh. appendiculatus as 
the chief carrier of the disease. Further investigations by Lounsbury 
(1906) served to include Rh. evertsi, nitens and capensis among the 
pathogenic species: “ In all cases the infection has been derived by the 
transmitting tick in one stage of its individual life cycle and communi¬ 
cated in the following stage.” 
Redwater and East Coast Fever may be said to resemble each other 
in that both diseases are conveyed by ticks, but whereas P. bovis 
persists in the blood, for a considerable length of time after recovery 
and recovered or “ salted ” animals are capable of infecting ticks, the 
contrary holds for T. parva. 
In short, there are ample grounds for referring the parasites of 
Redwater and East Coast Fever to different genera. We shall see that 
our studies upon the parasite, both living and in stained preparations, 
support the view that the parasites are very different. 
Our observations were conducted upon the blood of two cows which 
were experimentally infected by means of ticks ( Rhipicephalus evertsi, 
Js and ? s) imported from South Africa. Nuttall and Graham-Smith 
(This Journal, p. 208) have reported the negative results of their 
attempts at cultivating the parasites present in the blood of these cows. 
In both cases the parasites appeared at first in small numbers 
(5—6 °/ 0 ) and increased steadily in numbers until death when 60—75% 
of the corpuscles of the peripheral blood were found to be infected. 
The following protocols and charts relating to the two cows demon¬ 
strate the steady increase in the number of parasites on successive days. 
21_2 
