10 
liter of the culture as drinh, aud 6 agar slants. They ate most of the 
bread during the night, and drank a considerable quantity of the liquid. 
Two days following (April 13) they were given another liter of a young 
culture soaked on bread. On this day the rats seemed sick, 1 died. 
They ate little or none of the bread, but licked up all the liquid. On 
April 11, the third day, the rats were sick, very thirsty, refused food, 
2 were dead. From this on, the rats refused food and succumbed one 
after another until all were dead — 
Two days after feeding.. 
Three days after feeding 
Four days after feeding.. 
Five days after feeding.. 
Six days after feeding.... 
Died, 
. 1 
. 2 
10 
. 7 
Total 2' 
All these 27 rats, then, died within a week after being fed with an 
overpowering amount of the virus. 
The result, therefore, seems to depend on the amount ingested as well 
as the virulence of the cultures. 
RATS AXD MICE FED OX TOXINS. 
A toxin was made by growing the organism in flasks containing 1 
per cent peptone bouillon. The flasks were left over night in the incu- 
bator at 37° C., and then the growth continued at room temperature. 
At the end of two weeks the cultures were killed by exposing the flasks 
to 70° C. for several hours. The resulting product was fed to mice and : 
rats, and was found to produce a certain toxic effect. It seems very 
probable that the toxin favors the pathogenic action of the organism. ! 
This question, not having a direct practical bearing on this particular ; 
subject, will be discussed at another time. It may be stated here, how- 
ever, that animals fed on the toxin seem to acquire a certain amount 
of immunity against the virulent cultures. 
VARIOUS METHODS OF FEEDING. ; 
Eats were fed upon the organs (livers and spleens) of other rats dead 
of the infection, and in other ways, without producing any efi'ect. 
THE SURVIVORS FED ON LARGE QUANTITIES. 
Finally, I had about 60 rats, which had survived the various experi- I 
ments, on my hands. I fed them all with large amounts of cultures in ; 
order to get rid of them. They were given as much of the cultures as 
they could be induced to eat, every day for a week, without apparent 
efi'ect. The immunity produced is, therefore, very positive and lasts j 
at least several months. ! 
/ 
