104 REPOET OF THE BUEEATT OP A1SIMAL ESTDUSTET. 



of swine plague bacteria, the culture being about three days in 

 thermostat at 95 F. No disturbance whatever followed this feed- 

 ing. The animal was subsequently exposed to hog cholera (April 

 19) and died of the acute form of this disease. 



There is nothing to be added to the description given in the pre- 

 ceding report of the Bureau of the microscopic and biological char- 

 acters of the microbe of swine plague as obtained from the various 

 outbreaks. There is, however, a very marked difference observable 

 in their pathogenic effects. The organisms obtained from Sodorus 

 and Geneseo, 111., in the sumnier of 1886, both acted alike, while those 

 from Iowa and from the District of Columbia, studied in the winter 

 of 1887, also acted alike, but different from the two former. In the 

 preceding report a number of cases are cited in which subcutaneous 

 injections of cultures from the two first sources produced in pigs a 

 very marked sclerosis of the liver, with pronounced icterus. Neither 

 the organisms injected nor any other were found in the organs after 

 death. Fowls were also killed by large doses and presented exten- 

 sively local lesions. The organisms from the two latter sources had 

 no effect upon pigs when injected hyppdermically, even when very 

 large doses were given. Fowls were likewise undisturbed after in- 

 oculation. On rabbits the difference was also noticeable. Inocula- 

 tions of bacteria from the first class usually produced an extensive 

 plastic peritonitis, lasting nearly a week before the animal succumbed. 

 Inoculations of bacteria from the second class produced invariably 

 a septicaemia, fatal within twenty-four to seventy-two hours. Per- 

 itonitis was either absent or barely manifested. Whether this dif- 

 ference is due to an inherent difference in the bacteria or to surround- 

 ing circumstances, such as temperature, attenuation due to cultiva- 

 tion, etc., can not be determined at present. 



REMARKS ON THE CAUSATION OF SWINE PLAGUE. 



The difficulties attending investigations of diseases which have 

 their seat in the lungs, and which are presumed to be caused by spe- 

 cific bacteria, are due to the accidental presence of various other 

 parasites. The air, as it is drawn into the lungs, carries with it the 

 organisms suspended in it. From the mouth, which contains many 

 bacteria, some may be carried accidentally into the air tubes with 

 the saliva or food. 



When disease germs have obtained a foothold and produced a de- 

 struction of tissue or an infiltration by which the vitality of the tissue 

 cells has been greatly reduced, other bacteria may also gain a foot- 

 hold and multiply, although this may have been impossible in a nor- 

 mal lung. 



In examining sections of diseased lung tissue different forms were 

 found, no two lungs showing the same micro-organisms. Among 

 those which were found several times was a streptococcus, appearing 

 in the alveoli in the form of long chains. These chains were im- 

 bedded in the mass of cells which filled the alveoli. In some sec- 

 tions groups of cocci, in others masses of bacilli were observed. 

 Finally in the early stages bacteria were very scarce, and if the dis- 

 ease ran a very rapid course only the bacteria, which we regard as 

 the cause of this disease, were present in large numbers. When por- 

 tions of the luii'g tiss~tte 'die'd a'nd theft appeared ^V homogeneous 

 masses' imbedded in diseased but still living tissue, bacteria of every 



