MICHIGAN ACADEMY OF SCIENCE. 



107 



TABLE IV.— GUINEA PIGS. 

 (a) Inoculated with blood from rats. 



(b) Inoculated with blood from guinea pigs. 



Animal number. 



167 

 253 

 254 

 255 

 316 



403 



136 

 147 

 196 

 309 



310 

 337 

 386 

 429 

 432 

 451 



I. C. 



D. I. 



4 



7 

 22 



9 

 13 



48 



10 

 31 

 33 

 43 



10 

 49 

 32 

 19 

 22 

 26 



A. I. 



P. F. 



18 

 43 

 62 

 80 

 61 



162 



28 

 110 



92 

 104 

 142 



81 



1-2 gtt. 

 1 gtt. 



1 gtt. 



2 gtts. 

 1 gtt. 



10 



15 



15 



1-5 



1-10 



S. S. of mashed heart of rat 



dead about 10 hrs. 



Ill I 1 gtt. i 50 



97 ; 1 gtt. 15 



99 I 1 gtt. 1-2 



81 ' 1 gtt. 10 



1 gtt. 



1 gtt. 



2 gtts. 

 1 gtt. 

 9 gtts. 

 1 gtt. 



10 

 10 

 5 

 5 

 1 

 5 



P. I. 



I. P. 

 I. P. 

 I. P. 

 I. P. 

 I. P. 



I. P. 



S. C. 



s. c. 

 s. c. 

 s. c. 



s. c. 



s. c. 

 s. c. 

 s. c. 

 s. c. 

 s. c. 



Note. — S. S. — A suspension made in a sterile physiologically salt solution. 



The guinea pigs that were inoculated intraperitoneally had on the average 

 a shorter period of incubation than those inoculated subcutaneously, either 

 with blood from a rat or from a guinea pig. The duration of infection is 

 in favor of the subcutaneous method of injection as is seen from the above 

 tables. Guinea nig No. 403 is an exception. This is due probably to the 

 organism being attenuated by its living in the dead guinea pig so long. 



The length of the incubation period is not alwavs a sure guide as to the 

 duration of infection, as is seen by Nos. 10, 14, 189, 255, 136, 316 and 429. 

 Notice the difference in the incubation period and the duration of infection 

 in guinea pigs Nos. 309 and 310. These animals were inoculated at the 

 same time with blood from the same animal, yet the former was four times 

 longer in showing the infection and lived nearly three times longer than 

 the latter. Compare these with 337, which had three times as much blood 

 injected, but yet lived longer than the two together. 



From the above records, the following conclusion can be drawn: The 

 smallest amount of virulent blood that will infect, with subcutaneous inocu- 

 lations, will generally give a longer duration of infection than the same 

 amounts Avith intraperitoneal injections. 



Another interesting thing that was noted in the study of these records was 

 the disappearing and reappearing of the organisms in the l)lood of the ani- 

 mals. This was quite marked in the blood of the guinea pigs, due probably 



