CONTAGIOUS DISEASES OP DOilESTICATED AXDIALS. 423 

 IN'OCfULATION FE,03I EAT AKD LA3IB NO. 7. 



In my last report, page 101, I reported suspicious lesions in a rat in- 

 oculated with swine-plague virus and more characteristic symptoms in a 

 pig inoculated from this rat. In No. 7 of the present report will be found 

 the full record of the pig in question. By a reference to this record it 

 will be seen that without much elevation of temperature this pig showed 

 a purple cutaneous eruption on the fifth day and enlarged glands on the 

 twelfth, when it was inoculated with bloody mucus from the anus of the 

 infected lamb. After this the symi>toms became much more severe, and 

 when killed, twenty-two days after, the pig showed unequivocal symp- 

 toms of the affection. Whatever may be concluded as to the result of the 

 infection from the rat in this case, it is at least a further corroboration of 

 the position that the inoculated sheep is infecting. To further test the 

 susceptibility of the rodent, the following exi)ei''iments were undertaken: 



rNOCULATIONS FROM Pia, EAT, AND LABIS. 



The subject of this experiment was a female Sufiblk pig presented by 

 Cornell University, having been the smallest of the litter. It was about 

 three months old, small for its age, and very fat and sluggish. It was 

 first inoculated with albumen which had been charged with a drop of 

 blood containing bacteria, from pig No. 13 (see report page 90), and had 

 been cultivated in three succeeding portions of albumen drawn on each 

 occasion from a fresh, newly-broken egg, through a tube that had been 

 previously heated to redness to destroy all organic life. For fifteen days 

 nothing more was shown than a few purple spots and patches on the 

 rump, tail, and hocks. 



The subject was again inoculated with the congested intestine of the 

 rat which had died two days after the inoculation. The intestine had 

 been frozen over night. For thirteen days more the same equivocal 

 symptoms continued. 



A third inoculation was now practiced, this time with bloody raucns 

 from the anus of the lamb, diluted with a weak solution of common 

 table-salt. 



Twenty-two days after the third inoculation the pig was sacrificed, 

 and beyond some pigmentation of the lymphatic glands presented no 

 distinct lesions that could be held characteristic of the specific fever. 

 In short, the animal had suffered so slightly, if at all, that it might weU 

 be set down as a case of in8uscej)tibility. This is only what was to be 

 expected, as in the case of all plagues and contagia a certain number of 

 animals will successfully resist exposure and escape, though the infec- 

 tion is most virulent and concentrated. The number of my subjects was 

 too small to allow of any satisfactory general estimate; but, so far as it 

 goes, it shows one insusceptible animal in twenty-five, or at the rate of 

 five per cent. It may, however, be questioned whether the pigmenta- 

 tion of the lymphatic glands did not imply a previous mild attack of the 

 disease, and whether the apparent immunity in the later inoculations 

 was not due to the protective influence of the previous illness. 



SUCCESSFUL INOOULATTON OF A EAT— NO. 9. 



This subject was inoculated February 5, 1879, with virulent matter 

 that had been preserved for seventy-eight days, closely packed in dry 

 wheat-bran. The rat was preserved for thirteen days, and finally killed 

 Februai^ IS, and dissected immediately after death. The guttural lym- 



