zY-s Pathology mid Mrfhods of Protective Inoculation. .'501 



way interfered with the action of the virus. Where, however, this 

 serum was used to inoculate animals which were already infected, a 

 very curious change in the character of the disease occurred. 



The animals became affected, usually in thirty-six hours, with 

 hsemoglobinuria, which later passed into hsematuria and ended in- 

 variably fatally, if the disease was virulent. In two cases, however, 

 where the disease had been induced by an attenuated virus, the 

 haematuria came to an end with the subsidence of the fever. In all, 

 this curious condition was produced by serum in nineteen cases. 



Where animals are bled into citrate solution, the plasma is of a 

 yellow colour, but in cases which eventually became the subjects of 

 haematuria, I noticed, if they were bled about twenty-four hours pre- 

 vious to the onset of this condition, that the plasma was red coloured. 

 It is therefore evident that the condition has its origin in the blood. 



In several cases animals, which were partially protected, became 

 subject in a slighter degree to this complication, if they were re- 

 inoculated with virulent blood and were unable to resist it. 



This blackwater may have some relation to the blackwater fever in 

 man. It is generally believed in Rhodesia that blackwater does not 

 occur as a primary disorder, but only supervenes in persons who have 

 previously been the victims of malarial fever. 



It seemed to me that this serum might in some way be associated 

 with a residual infection. To determine this I inoculated a " salted " 

 horse, which had also had repeated large injections of virulent blood, 

 with 50 c.c. of fresh blood. I bled it eight days later, and with 5 c.c. 

 of its blood inoculated a clean animal, which thereafter had a very 

 slight rise of temperature on the eighth day. 



An animal similarly treated was finally inoculated with 300 c.c. 

 injected intravenously and 20 c.c. subcutaneously thirty-nine days pre- 

 vious to being bled. When bled, the blood was defibrinated, and 

 100 c.c. was injected into each one of six animals. No evidence was 

 shown of any infectivity of the blood. 



I now determined to make use of the serum from animals which, 

 under Clause 3, had been allowed to rest for periods over one month 

 previous to the collection of their serum. 



This serum is that which is now being used for the purpose of pro- 

 tective inoculation. 



I have determined with regard to it 



1. It possesses no curative action which in practice would be of any 

 avail to restrain the course of the disease. 



2. Since an injection of 100 c.c., into one animal has absolutely no 

 effect in restraining the action of 1 c.c. of ordinary preserved virus 

 inoculated subcutaneously on the other side, it does not possess any 

 immunising power which would be of practical value in withstanding 

 infection. 



