Sessional_Paper_1903 — Page 610

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Appendix E.

EXPERIMENTAL. INVESTIGATION.

This part of the investigation has been prosecuted to a limited extent, indeed only so far as to place the micro-organism which has been isolated from cases of the disease upon an irrefutable basis and to determine whether it fulfils the postulates of KocH. Having satisfied ourselves in regard to these points, we have, apart from a few preliminary experiments, decided to postpone this important part of the research. It is proposed to deal fully with this part of the investigation in a later

report.

In the first place, feeding experiments were resorted to. Small pieces of the internal organs, e.g., the lymphatic glands, spleen, &c., were given to a number of fowls. The condition of these animals including their body temperature was regularly noted. Although these animals were fed upon considerable quantities of infected tissues no reaction was obtained, all maintaining a perfect state of health,

Further numbers of fowls were allowed to wander about the shed in which the sick animals were kept, and on opportunity presenting itself, all of them vora- ciously fed upon the intestinal excreta of the sick animals. Sometimes large quantities of solid or semi-solid masses of necrosed tissues and casts of the bowel were devoured by these animals and although the fowls were wandering about the shed during the greater part of the summer and picking up what excreta they could find, only in one instance was a fatal result obtained. This fowl was examined bac- teriologically and in its blood and internal organs the specific bacillus was found.

Again, large numbers of pigeons were constantly present in the infected shed and although they readily fed on the infective material passed per rectum by the sick animals, only one of these was found dead, its blood containing the charac- teristic micro-organism. From these results-although only preliminary-one is thoroughly justified in concluding that so far as feeding experiments are concerned these animals-fowls and pigeons-are extremely resistant.

The results obtained by the feeding of animals of the same species as those diseased, with blood and pieces of the internal organs obtained from the fresh dead body of a diseased animal were highly satisfactory

For details in regard to this experiment vide "Heifer Calf D.”

The disease in this animal ran a typical course. It was marked by a high temperature, characteristic diarrhoea, rigors, &c., during life, and the subsequent post- mortem and bacteriological examination proved the conditions present to be due to the disease under consideration.

The foregoing completes our experimental data obtained by feeding. Highly interesting results were obtained in one bullock by the subcutaneous inoculation of fresh blood taken from a diseased ox. For details in regard to this experiment vide Bullock A." The disease in the inoculated animal ran a typical course and gave characteristic post-mortem and bacteriological results.

C

As already mentioned experiments were undertaken with pure cultures of the bacillus which had been isolated from the disease. These experiments were of a limited number and only proceeded with as far as the point where a conclusion could be drawn as to the causal relationship of the micro-organism to the disease. Inoculation and feeding experiments with the culture were carried out on small animals as mice, rabbits, guinea pigs and birds. The result obtained was subject to considerable variation. Fresh strains of the bacillus recently isolated from a dead animal gave in the majority of cases a positive result. Each species of animal dying rapidly from septicemia. The bacillus could be recovered from the bodies of these dead animals with little difficulty. Cultures of the micro-organism which had been growing in the laboratory for some time gave in the majority of instances a negative result. This apparently depends upon the very rapid diminution in virulence of the bacillus when grown upon artifical nutrient media. Experiments in regard to this question will be dealt with fully in a later report.