ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
793 
action being guinea-pigs. Thus, a guinea-pig weighing 385 grammes 
died eleven days after the inoculation of 0*7 ccm. of a 1 in 150,000 
solution of ricin, the post-mortem examination showing characteristic 
haemorrhages in the alimentary tract. One gramme of this substance 
might therefore prove fatal to 1,500,000 guinea-pigs. White mice, on 
the other hand, did not die after much larger doses, and this immunity 
of mice against this poison might be increased by subcutaneous injections 
of ricin. The same result might be obtained, however, far more easily 
and without any chances of failure, by feeding mice with ricin. It was 
best to begin with small harmless doses, gradually increasing the amount 
until the organism was accustomed to the poisonous substance. In ten 
days a mouse might then be inoculated with a deadly or even larger dose 
without suffering any evil effects. Thus, whilst doses of 1/200,000 
gramme were absolutely fatal in normal animals, mice fed daily and in 
increasing quantities with ricin suffered no harm after the injection of 
1/1000 gr. or 1/500 gr., or, occasionally, of 1/250 gr. 
Whilst a 0*5 or 1 per cent, solution of ricin applied to the eye of a 
normal animal produced severe inflammation and panophthalmitis, the 
application of a 10 per cent, solution of ricin produced no effect on the 
eye of an animal previously fed with ricin. In other words, this was 
distinct proof of the existence of a local as well as of a general immunity 
against the poison. Strangely enough it was almost impossible to 
render the subcutaneous tissue immune against ricin, and even in 
exceedingly immune animals the subcutaneous injection of ricin pro- 
duced distinct necrosis of the subcutaneous tissue. 
It was a remarkable fact that this immunity appeared quite suddenly 
on the sixth day, and then increased slowly, so that on the twenty-first 
day the animal could stand a dose which was 400 times higher than that 
fatal to a normal animal. 
This immunity against ricin appeared to be permanent, for it was 
still present in immune mice which had not taken ricin for a period of 
six months previously. 
He had been able to extract from the blood of animals rendered 
immune against ricin a body which had the power of counteracting the 
toxic action of ricin, so that a powerful solution of ricin was rendered 
harmless by admixture with the blood of immune mice. It was also 
possible to render animals immune against ricin by injecting the blood 
of immune animals. 
Hr. Kitasato, of Tokio, shortly summarized the results which he and 
Dr. Behring had obtained with the virus of tetanus. According to 
these observers, the blood Of a normal rabbit has no influence on the 
toxines secreted by the bacillus of tetanus. But when a rabbit had been 
rendered artificially immune against that disease, its blood had the 
power of destroying the toxines secreted by the specific bacillus. Nay, 
more, the blood of rabbits made artificially immune against tetanus with 
trichloride of iodine, rendered mice not only refractory to tetanus but 
also cured the disease when already in progress. The blood, however, 
did not appear to act on the tetanus bacillus itself, but on the toxines 
secreted by the bacillus. 
Dr. Adami thought that it was impossible to doubt that in a large 
number of infectious diseases the process of phagocytosis was extremely 
1891. 3 K 
