64 
Transactions of the Boyal Society of South Africa, 
Before discussing the question of Koch's bodies, I wish to make some 
remarks on P. parvum. Last year Ollwig, at the Congress of Micro- 
biologists in BerUn, stated that P. parvum and P. mutans were identical. 
My experiments leave no doubt that P. parvum and mutans are two 
different organisms, which view has been held for a number of years by 
different authors. Blood containing P. parvum in extraordinarily large 
numbers was injected subcutaneously and into the organs of various 
animals, and in no instance was an infection transmitted. On the con- 
trary, it was an easy matter to transmit P. mutans to a healthy beast. An 
emulsion of 1 c.c. red corpuscles in 10 c.c. saline solution was sufficient to 
do so. As a further proof, it may be stated that Ehipicephalus appendi- 
cidatus in the Transvaal transmit P. mutans only in exceptional cases. 
P. parvum and P. mutans are therefore, luith regard to their pathoge^iic 
effect, tiuo different parasites luhich also shoiu differences in their cycle of 
development. 
Together with the daily blood examinations, systematic punctures of 
glands and spleen were made. On comparing preparations from cattle 
suffering from East Coast Fever with those infected with P. mutans no 
doubts can be left about the cause of East Coast Fever. Shortly before 
the parasites appear in the blood one will notice segmenting forms of 
Koch's bodies which throw off a great number of parasites. For this 
investigation the large shoulder glands are the most suitable. Neither an 
infection with P. higeminum nor one with P. mutans, P. equi, or P. canis 
shows similar evolution forms, whereby it is proved that Koch's bodies 
represent a stage in the development of P. parvum, as already Koch him- 
1 
