BUREAU OF ANIMAL INDUSTRY. 115 



of these carcasses were tested at intervals by chopping. up some of 

 the meat and feeding it to nonimmune pigs. It was found that in 

 summer the infectiousness disappeared from the buried and un- 

 buried carcasses alike as a rule within 7 days, there being only one 

 exception to this. In winter, however, the virus remained alive and 

 active for several months. These experiments thus agree in the 

 main with those with infected pens. The infectiousness is of short 

 duration in summer but continues for long periods in winter. The 

 natural conclusion is that the processes of putrefaction and decay 

 destroy the vitality of the hog-cholera virus. 



It has been generally believed that the hog-cholera contagion is 

 commonly and frequently conveyed on the shoes of farmers and on 

 the wheels of wagons and other farm equipment. A number of ex- 

 periments have been carried out to determine the likelihood of the 

 disease being carried in such a manner. This work is incomplete, 

 but the experiments already finished permit a partial report. Pens 

 of pigs affected with cholera were maintained at a distance of from 

 50 to 100 yards from pens which contained healthy, nonimmune pigs. 

 Two men daily entered the pens with the sick pigs, and after walk- 

 ing through the pens and handling the sick animals they walked im- 

 mediately to the pens containing the healthy animals a short dis- 

 tance away and entered the pens with them. In one case healthy pigs 

 were exposed daily in this manner for 60 days in all and yet re- 

 mained practically well. Thes experiments are being continued, 

 3^et sufficient data have already been obtained to make it clear that 

 hog cholera is not readily conveyed on the feet of attendants and 

 that probably this channel is not so important in spreading the dis- 

 ease as has been generally believed. 



CAUSE OF HOG CHOLERA. 



Extensive bacteriological studies liave been made of the organs 

 and body fluids of sick hogs in order to discover the exact nature 

 of the virus of hog cholera. Many interesting observations have 

 been made, but no final conclusion has been reached. 



PRODUCTION OF ANTI-HOG-CHOLERA SERUM. 



During the fiscal year there was produced approximately 3,000,000 

 cubic centimeters of anti-hog-cholera serum, of which about 550,000 

 cubic centimeters was sent out for use by inspectors in the field. 

 Approximately 24,000 cubic centimeters of virus was supplied for 

 use with the serum in applying the simultaneous inoculation against 

 hog cholera. Numerous commercial establishments were supplied 

 with small quantities of standard virus for use in serum production,, 



DIPS AND DISINFECTANTS. 



The laboratory of dips and disinfectants received for examination 

 300 samples of live-stock dips, disinfectants, and miscellaneous 

 materials. 



During the calendar year 1916 there were sent out the following 

 test outfits and supplies for making tests of dips in the field: Two 

 hundred and ninety test outfits for arsenical dips, supplies for making 



