426 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



fore it was sacrificed, proved more severe, but did not reach a fatal re- 

 sult ; a third ( No. 8) was inoculated twenty-tvro days before its death, 

 and showed such slight symptoms and iwst mortem lesions that it might 

 have been questioned whether it really had the disease ; a fourth (Xo. 

 5), inoculated twelve days before its death, had very slight symptoms 

 and lesions of the disease; while in a fifth (So. 6). that lived for the 

 same length of time after inoculation, the symptoms were more severe, 

 but there was no certain indication of a fatal result. 



Of the pigs inoculated from the rat, two (N os. 1 and 7), inoculated 

 from the first rat, had such slight symptoms that they were afterward 

 inoculated from the lamb, and the third (No. 10) inoculated from the 

 second rat, twenty days before it was killed, showed moderate but dis- 

 tinctly marked symptoms, and was manifestly improving when it was 

 sacrificed. 



Inoculations from the infected rabbit were more redoubtable. One pig 

 (No. 8, Add. I), inoculated twice from the rabbit and killed on the four- 

 teenth day after the last inoculation, was suffering severely and might 

 have died. Another (No. 9, Add. 1) was so ill on the twentieth day 

 after the inoculation that he could not have survived many hours longer. 



These facts point to the most important conclusion that the poison 

 of the swine plague, when passed through the system of the sheep or 

 rat, becomes lessened in virulence, and usually conveys the disease 

 back to the pig in a non-fatal form. Should this be sustained by 

 further experiment, and should this, like some other bacteridian dis- 

 eases, so affect the system that a second attack is rendered much milder 

 or entirely prevented, it will open the way for a system of vicarious in- 

 oculation that will save our swine breeders from the yearly losses of tens 

 of millions that now threaten the very existence of this industry. It is 

 noticeable that the pig (No. 5) inoculated from the pig infected from the 

 lamb, and therefore by poison the second remove from the ovine sub- 

 ject, though showing symptoms of the disease, did not suffer severely 

 in the twelve days it was allowed to sur\'ive, so that the mitigation of 

 the poison may remaiu for some generations after it has once passed 

 through the slieep. 



That a further inquiry in this direction promises valuable results 

 may be further deduced from recent developments in anthrax and 

 chicken cholera. 



In February, 1878, Bnrdon Sanderson and TTilliam Duguid, at Brown 

 Institution, London, inoculated gidnea-pigs with the poison of the an- 

 thrax, and conveyed the disease from guinea-pig to guinea-pig for sev- 

 eral generations of the poison. From different guinea-pigs it was 

 inoculated back upon two yearling heifers and a six months' calf, and 

 in all produced active disease, but in no case with a fatal result. Re- 

 coveiy in all cases might be said to have occurred by the fifth day. 

 The liquids from the guinea-pigs thus inoculated on the cattle were sub- 

 jected to the counter test of inoculation on other guinea-pigs, and in all 

 cases with fatal results. To test the effect on the system the calf was 

 reinoculated fifty-two days after the first, and the heifers nine days after 

 the first, with the efiect of producing a milder attack on the heifers, and 

 a severe but not fatal illness in the calf. 



Again, twenty-five days later, they were inoculated with anthrax 

 poison, cultivated in grain infusions, which makes a most virulent and 

 fatal preparation ; but, though two sickened, in none did a fatal result 

 ensue. 



Dr. Greenfield, who was in charge of the Brown Institution in 1879, 

 continued these experiments. A steer was inoculated four times in 



