Annals of the Transvaal Museum. 
241 
THE LIFE=CYCLE OF THEILERIA PARVA — THE CAUSE OF 
EAST COAST FEVER IN CATTLE IN SOUTH AFRICA. 
A GENERAL REVIEW. 
By Dr. Richard Gonder, at present in the Transvaal. 
(From the Government Veterinary Bacteriological Laboratory , Onderste- 
poort, Pretoria, South Africa.) 
In a previous communication* I reported on the developmental stages 
of Theileria parva ( Piroplasma parvum, Babesia parva) in the organs of 
cattle, and demonstrated the various stages, and I am now able to explain 
practically the whole life-cycle of this parasite. I then mentioned (1) that 
Theileria parva (as I call the parasite of East Coast fever), with Bettencourt, 
Franca, and Borges, cannot be identified with Babesia mutans (Piroplasma 
mutans) ; and (2) that the forms found in the organs of cattle represent 
a specific stage in its life-cycle, the forms of which stage are of great 
importance from a diagnostic point of view. Recent investigations have 
completely corroborated my previous statements. 
I divided the development of the parasite of East Coast fever in the 
organs into two generations — distinguishable by their morphology — i.e. 
agamogonous and gamogonous. As indicated by the name, the former 
signifies certain forms which multiply agametically, that is to say, forms 
which are not capable of performing a sexual function. It is only after 
the elimination of nuclear substance (reduction of nucleus) that parasites 
result from these agamogonous stages which develop into the gamogonous 
generation. The gamogonous generation then supplies sexual forms which 
copulate when they obtain access to the stomach of the transmitting 
host. 
It is generally known that every protozoon undergoes a process of 
fertilization in its life-cycle ; this fertilization acts on the organism as a 
regulating mechanism. The propagation or multiplication of the protozoon 
is not of necessity connected with fertilization ; it may precede or succeed 
it. In the course of the phylogenetic evolution of parasites, and especially 
of the blood protozoa, a definite alternation of generations has developed. 
The original host is undoubtedly the transmitter (Ektoparasite) in which 
copulation and the succeeding encystment or an agamagonous development 
takes place. In the intermediate host (man or animal) the further agametic 
multiplication proceeds, ending in the progamogonous or gamogonous 
generation, that is to say, with the formation of the proper sexual individuals. 
The latter are only able to undergo further development in the transmitting 
agent. 
i 
* Proceedings of Royal Society of South Africa, Capetown, and of Transvaal Biologica 
Society, Pretoria, July, 1910. 
