644 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



the sick and dying in an infected pen._ It was soon found that the 

 inoculations were by no means protective in whatever way the virus 

 entered the system. Feeding usually produced cases of the most 

 acute character and with the most severe and extensive lesions. The 

 doses of inoculated cultures were gradually increased in quantity 

 without yielding any better results. Of a large number of animals 

 subjected to inoculation only five took the disease unmistakably as a 

 consequence of the operation. 



This method of protective inoculation having failed with unatten- 

 uatod cultures, there seemed no necessity for atteinpting any investi- 

 gations with attenuated cultures. The experiments, including tables 

 and post mortem notes, are given in extenso as they were made. In 

 reading them over it will be noticed that the virus was cultivated 

 chiefly in liquid media, and the solid media, more particularly nutri- 

 tive gelatine, were only employed to test the purity of the cultures. 

 Whenever these cultures were used for inoculations they were pre- 

 viously tested on gelatine plates by drawing a platinum wire, dipped 

 into the culture, through the gelatine layer two or three times before 

 the gelatine had become solid. Among the hundreds of cultures thus 

 tested in the space of several months not one was found impure. 

 Series of cultures extending up to the tenth generation were usually 

 carried on by inoculating fresh tubes each day. The last culture 

 tested as described above gave precisely the same colonies as the first 

 in all the series thus far prepared. Tlie culture tube described in the 

 first annual report of the bureau was used almost exclusively for 

 these cultures in liquid media. The advantages and accessibility of 

 cultures in liquids for purposes of inoculation; the readiness and ease 

 Avith which quantities or doses may be determined, finally, certain 

 characteristics of growth in liquids, place this method on a level Avith, 

 if not above, that of solid cultures for experimental purposes. For 

 diagnostic purposes solid media are to-day a sine qua non of bacteri- 

 ological work. 



Experiments. — Pigs Nos. 152, 1G7, 168, and 175 were inoculated 

 with pure cultures in beef -infusion peptone as follows : On January 23, 

 one drop of the seventh culture, derived from the spleen of pig No. 114; 

 on February 8, with i*'= from a culture derived from a guinea-pig (No. 

 4). Both cultures were diluted in sterile normal salt solution in such 

 a way that l*'" of fluid was injected each time. The inner aspect of 

 the thigh near Poupart's ligament was chosen. The liquid was intro- 

 duced beneath the skin into the subcutaneous tissue with a hypoder- 

 mic syringe. There was no perceptible swelling at the site of either 

 inoculation, excepting in No, 175, in which there were two nodes, each 

 of the size of a walnut, at the seat of the first inoculation. In order 

 to test the extent of the immunity which these inoculations may have 

 conferred, feeding the viscera of pigs which had succumbed to hog- 

 cholera was resorted to, the animals being transferred to the large in- 

 fected pen for this purpose. Nos. 168 and 175 were fed in this way 

 March 5, and two animals not inoculated (Nos. 158 and 159) were fed 

 with them. All four died, the two vaccinated animals in about twenty 

 days, the others in about fifteen days after feeding, March 13, Nos. 

 152 and 167 were fed with two check animals Nos. 176 and 190. These 

 four also died of hog-cholera; the two vaccinated ones averaging 

 twenty days, the others eleven days after feeding. The inoculation 

 may be said to have simply retarded death from five to nine days. A 



