215 
NOTES ON IMMUNITY IN CANINE PIRO- 
PLASMOSIS. 
By GEO. H. F. NUTT ALL, F.R.S. and G. S. GRAHAM-SMITH, M.D. 
CONTENTS. 
PAGE 
Introduction.215 
1. Attempts at immunization by means of 
(а) Immune serum (earlier experiments by Noeard and Motas, 
and Robertson) ........ 215 
(б) Inoculation with blood containing dead parasites (Authors’ 
experiments) ......... 218 
2. The duration of “immunity” following upon “recovery” . . 222 
3. The persistence of parasites in the blood of apparently recovered dogs 223 
4. Records relating to the passage of P. canis through series of dogs . 225 
The discovery by Nuttall and Hadwen (vi. 1909, This Journal, 
vol. II. p. 156) that trypanblau and trypanrot exert a curative effect 
upon canine piroplasmosis, leads us to publish the immunization 
experiments described in this paper, although they have not yielded 
promising results. We do not consider that further experiments of the 
kind are required since there is little evidence that they will lead to a 
practical means of protecting dogs against piroplasmosis. On the other 
hand the drug treatment referred to gives us a means of curing the 
animals, and, combined with previous inoculation with virulent blood, 
affords us a practical means of “ salting ” animals without there being 
much risk attached to the procedure. 
1. (a) Attempts at immunization by means of immune serum. 
(Earlier experiments by Nocard and Motas, and Robertson .) 
It will be remembered that Nocard and Motas (1902) reported upon 
experiments which indicated that immune substances are developed in 
the serum of dogs that have recovered from piroplasmosis. Their 
