Abstract
The experiments briefly reported here were undertaken in order to learn whether the resistance of rats to pneumococcus could be increased by feeding them the tissues of animals killed by injections of the same organism. It was thought that if a toxic substance is formed in the tissues of an infected animal, and if such a poison were even only partially absorbed from the intestines of the rats to which the tissue was fed, the formation of an antitoxin might be expected. As a result, an increased resistance to injections of the living organism would perhaps follow. Consideration, however, of the immunity experimentally produced in such diseases as typhoid, tuberculosis and diphtheria by the oral administration of the organisms causing these diseases suggested that the pneumococci present in the tissue being fed might be partly or even wholly responsible for any protection which might be created.
A number of rats from a single source was divided into two groups, one (control) was fed the tissues of healthy rats, the other (experimental) the tissues of rats killed by intraperitoneal injections of pneumococcus Type I. Following such feedings for a period of about three weeks, with a daily average ingestion of approximately seven grams per rat, controls and experimental animals were tested. A 24 hour blood broth culture of the same germ was used.
The results of One experiment are given in the accompanying table. The data show that the experimental rats survived 1000 or more times the dose which proved fatal for control rats of equal weight. Similar results were obtained on a somewhat larger number of animals in another experiment.
The effect of feeding the living pneumococcus alone was also studied. Varying numbers of cocci were fed.
Get full access to this article
View all access options for this article.