G. H. F. Nuttall and G. S. Graham-Smith 217 
with the mode of treatment the experimental dogs may be grouped in 
4 categories as follows: (a) four dogs received the immune serum 14 
days before they were inoculated with virulent blood. (6) Two dogs 
received injections of immune serum simultaneously with the injections 
of virulent blood; in the one case the latter was mixed with the immune 
serum prior to injection, in the other case the injections were made 
separately on opposite sides of the dog’s body, (c) One dog received the 
injection of immune serum five days after inoculation, (d) Two dogs 
received injections of immune serum every day after they showed fever 
following upon inoculation with virulent blood. 
All of the nine dogs died, but in the case of the last two ( d ) no para¬ 
sites could be detected in their blood at death. Robertson remarks 
that the results of his treatment by means of immune serum did not 
appear promising. He refers to the absence of parasites in the two dogs 
(■ d ) as being of interest. 
This observation certainly does possess interest since we have always 
found parasites in the blood of dogs dying from the disease. We have 
only observed two analogous instances: 
(1) In a dog which was treated with try panrot when in an advanced 
stage of piroplasmosis ; in this case the parasites disappeared on the 5th 
day after treatment and could not be found in the blood subsequently. 
(Nuttall and Hadwen, Dog 2, p. 174, This Journal .) 
(2) In Dog 1 (see p. 219), reported in this paper, which we sought 
to render immune by preliminary treatment with blood containing dead 
parasites. In both of these dogs parasites had been previously detected 
in the blood. Robertson does not state whether parasites were present 
in the blood of his two dogs at an earlier stage but presumably they 
were present since he notes that the dogs had fever. It appears from 
these cases as if a partial immunity had been attained, but the experi¬ 
ments are too few in number to be conclusive. Moreover, if the dogs 
had survived longer the parasites might have reappeared after the 
manner observed in the dogs treated by Nuttall and Hadwen by means 
of drugs. 
(See Summary (1) on p. 225.) 
Owing to the limited facilities for keeping dogs in our Cambridge 
laboratories it has been found impossible to repeat the experiments by 
Nocard and Motas, and Robertson. We however carried out other 
experiments in the hope that they might lead to results possessing 
practical value. We have been disappointed in this hope, and see no 
