70 Transactions of the Boyal Society of South Africa. 
To understand this explanation it may be stated here that Smith and 
Kilborne undertook their experiments usually in July, August, and Septem- 
ber, and it was during September, October, and November that they met 
with the disease due to the coccus-like bodies. In subsequent observations 
made in South America by Knuth, the same coccus-like bodies were seen 
again. This author did not support the view of Smith and Kilborne about 
the three different stages, yet nevertheless he considered the coccus-like 
bodies to belong to the life cycle of P. bigeminum. On the other hand, 
Djunkowsky and Luhs, who were studying the piroplasms in the Trans- 
causcasus, came across the same parasite ; they had noticed the presence 
of P. bigeminum in that country, but they did not identify the coccus-like 
body with this disease, but with another one, which they called tropical 
piroplasmosis, and which is due to a small piroplasm called P. anulatum, 
very likely identical with our P. parvum. 
In South Africa I have seen these parasites for a number of years. 
The American literature not being available to me at the beginning of my 
investigations, I described them as marginal points in my various reports. 
The observations which I made led me to think that these marginal points 
had nothing to do with P. bigeminum, but that they represented an inde- 
pendent parasite genus of their own, and that they were the cause of 
a definite disease, which had to be separated from Eedwater. I was, 
however, until recently, unable to give this proof in such a way as would 
remove all doubts. 
Some years ago I sent ticks {Boophihis decoloratus) to England which 
were infected with P. bigeminum. They produced the disease in London 
when placed on an ox, and this ox formed the starting-point of many 
investigations and inoculation experiments undertaken in England. As a 
result of such investigations Nuttall described the cycle of development of 
P. bigeminum in the blood, and, according to this author, it is a simple 
division, as in the case of P. canis. He does not mention any forms 
corresponding to the coccus-like or marginal points mentioned before. 
In Germany the disease Hsemoglobinuria of cattle was also investi- 
gated during the last few years ; it was found to be due to a piroplasm 
which, owing to some slight difference, is considered to be a species of its 
own, and is called P. bovis, but it is very closely allied to P. bigeminum. 
No parasites resembling the peripheral coccus-like bodies were noticed in 
the life cycle of this parasite. 
Stockman and myself have carried out, for a number of years, 
experiments to immunise English cattle. The cattle were inoculated in 
England against South African Eedwater with the strain of Eedwater 
forwarded by means of the already mentioned ticks ; after the inoculation 
the animals were sent to the Transvaal to be exposed here. In the first 
lot of cattle exposed I noticed the appearance of marginal points in the 
