72 Transactions of the Boyal Society of South Africa. 
that the inoculation of such blood would constantly cause Redwater in the 
first instance. An observation I had made showed that animals imported 
from Aliwal North, although promptly reacting to Redwater, did not do so 
to the injection of blood containing marginal points. I concluded, there- 
fore, that these animals are immune against this latter parasite. It had 
to be expected that when blood of such animals was injected into 
susceptible animals, only marginal points would appear. This has been 
done in several instances, and in every one, after a typical long incubation 
time, marginal points alone appeared. After recovery the animals were 
injected with P. higeminum of a pure infection ; the result was that they 
showed this parasite after the usual period of incubation. Thus the 
independence of marginal points to the cycle of P. higeminum was demon- 
strated in the reverse order. Accordingly, no doubt can any longer be 
left that these peripheral bodies represent a genus of their own which 
produces a specific disease in cattle. 
I have proposed to give the name Anaplasma marginale to this 
parasite. This anaplasm is transmitted by ticks, and it is a noteworthy 
fact that the incubation time by tick transmission is much longer than 
that after inoculation of the animals with blood ; in the experiments 
carried out by me it varied from fifty-five to seventy-five days. Accord- 
ingly we understand the results of experiments of the Americans, which 
were started in the summer. They exposed cattle to tick infection ; they 
noticed the appearance of P. higeminum first, having a shorter iDcubation 
time, and only later in the year, after the long incubation time, they 
noticed the appearance of Anaplasma marginale. 
It has already been indicated that blood of an immune animal is 
infective ; such an animal forms the reservoir of the virus. This is a 
peculiarity of the piroplasma diseases, to which group anaplasmosis also 
belongs. It may be of interest to state my opinion that anaplasmosis is 
probably the disease which the farmer has hitherto called Gall Sickness. 
Up to the present time we know of three different parasites in South 
Africa which are found in the blood of immune cattle — P. higeminum, 
P. mutans, and Spirochceta theileri — and to these will now be added 
Anaplasma marginale ; they can all be transmitted by the inoculation 
of blood and by ticks. 
