insusceptibility

Insusceptibility is occasionally met with, both in the cow and in man, but it is very rare.

Some individuals are refractory to vaccination, but complete insusceptibility is exceedingly rare.

Thus animals may prove refractory to a small dose of the poison of anthrax, yet Chauveau has shown that this virus will overcome all native or acquired insusceptibility when administered in excess.

As illustrative of insusceptibility may be quoted the poodle of Hertwig, which was inoculated nine times with unquestionably rabic virus without effect; also the pointer of Rey, which was seventeen times bitten by rabid dogs without harm; also the acquired immunity of Galtier's sheep and rabbits, above referred to.

It may well be suspected that the relative insusceptibility of chickens is in part due to the large amount of animal food consumed by them, and that the chilling process increases the receptivity by deranging sanguinification and nutrition.