500 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Use of small Quantities of Virus in mitigating Effects of Inocu- 

 lation.* — The honourable rivalry in the extension of knowledge of 

 those diseases which depend on a contagium vivum is sustained by A. 

 Chauveau. He had been led to consider that as comparatively large 

 quantities of the poison of splenic fever succeed in producing an 

 immunity in sheep which are but slightly affected by it, so conversely 

 small quantities ought to do the same for individuals whose recep- 

 tivity for the disease is great. 



His experiments made to test this hypothesis showed that sheep 

 of the native French breeds are invariably killed by the disease when 

 blood containing about 1000 bacilli is introduced into the jugular 

 vein. The method adopted is to dilute infected blood from the 

 guinea-pig until a cubic centimetre of the liquid contains, according 

 to computation, approximately the required amount of the bacterium, 

 and then to inject this quantity, taking care to avoid extravasation. 

 With 600 bacilli to the cubic centimetre, out of two sheep, one died, 

 and the other survived and did not suifer at all in health. Another 

 sheep was infected with 50 bacilli, and at the same time 100 bacilli 

 were introduced into another with the additiim to the liquid of 1 per 

 cent, of carbolic acid ; in the former case a slight temporary fever 

 ensued, in the latter no inconvenience at all. Tliese two animals, 

 together with the one which survived the dose of bOO bacilli, and two 

 fresh ones, were experimented on together by injection of doses of 

 about 1000 bacilli each. In the case of the survivor of the second 

 experiment, ten days had elapsed since that experiment ; in that of 

 the other two survivors, seven days had intervened since their former 

 inoculation. In the present experiment all died of the disease ; but 

 one of them, a survivor of the former experiments, lived till the 

 seventh day, and was afflicted with a bacterial meningo-encephalitis, 

 probably indicating that it was already partially protected by the 

 former inoculation. Another five sheep were treated with a prepa- 

 ration of blood taken from the clots in the heart and from the spleen 

 of a rabbit that had been dead nine days but had been kept quite 

 fresh; 250 bacilli in ^ cc. of liquid were injected into each. All 

 withstood the dose, exhibiting only a slight and temporary fever. Of 

 these five, which were re-inoculated six weeks afterwards, four sur- 

 vived the second dose, and the remaining one died. It is possible 

 that the small quantity, and hardly fresh condition, of the liquid used 

 may explain this immunity. 



The same investigator deals also with symptomatic charhon, or 

 what he calls Chabert's disease, or bacterian, as distinguished from 

 hacteridian chaxbon, which is splenic fever. He is able to produce 

 immunity from its effects also by carefully graduated injections into 

 the connective tissue. Ten sheep were brought to a state of practical 

 immunity from splenic fever by injections extending over from eight 

 to fifteen months, when a curious but instructive accident took place. 

 A final injection of a very rich infusion was administered to all the 

 animals ; but owing to its having been filtered inadvertently through 

 a cloth which had not been cleaned after experiments with the other 

 * Comptes Rendus, xcii. (1881) pp. 844-8. 



