Lung Plague of Cattle. 651 



ized meat juice prepared as follows : fresh beef or veal, minced 

 and pulped, 500 grs., and water, i litre, are kept for 20 hours at 

 35° C, the liquid expressed, 5 grs. common salt added, mixed 

 in equal proportions with the peptonized liquid from the pig's 

 stomach, heated to 70° C. to coagulate albuminoids, filtered, alka- 

 lized and sterilized. To this mixture is added ^th part of 

 blood serum (sterile) from the rabbit or cow. 



This bouillon was inoculated with the pulmonary interlobular 

 exudate, enclosed in collodion capsules, having very thin walls, 

 and inserted aseptically into the abdomen of the rabbit. In 15 

 days the rabbit was sacrificed, and the capsules enucleated from 

 their envelopes of exudate and cells. The contents showed 

 the slightest possible shade of opacity, but they contained 

 neither cells nor anj' other definite organism. Under a magni- 

 fying power of 2000 diameters the liquid contents were found 

 to be full of brilliantly refrangent points, actively mobile, 

 but so minute that their form could not be made out even when 

 staining was resorted to. The contents of these capsules when 

 inoculated on cattle produced the unequivocal phenomena of 

 lung plague infection in a period of from 8 to 15 days. Other 

 collodion culture cases inoculated from this produced the same 

 cultures in the peritoneum of the rabbit. Collodion cases 

 charged with the uninoculated peptonized bouillon, and placed in 

 the rabbit's peritoneum remained ab.solutely clear, with no re- 

 frangency nor motility under high powers and with no infectivity 

 when inoculated. The rabbits used for the infective cultures 

 often became emaciated to the last 'degree and even died, but 

 their tissues proved in no respect infecting to culture media nor 

 when inoculated. The attempt to cultivate the germs in collodion 

 cases in Guinea pigs completely failed. 



This ingenious form of culture devised by Metchnikoff for ex- 

 periments on the more delicate organisms, has been used by No- 

 card to accustom the tubercle bacillus of mammals to grow in the 

 bird and opens up great possibilities for future investigators. 

 The collodion, being impermeable to leucocytes and bacteria, 

 allows these to grow almost together, only on the opposite sides 

 of the collodion wall, restrains phagocytosis, and protects the 

 microbe against the destruction which would otherwise overtake it. 



Modes of transmission. The exhalations from the sick convey 

 the infection to susceptible healthy cattle. Yet even this was 



