THE PHENOMENA OF INFECTION 451 



extract in a fresh state. Likewise, an inactivated normal 

 serum of the rabbit or the inactive serum of the guinea-pig 

 may be complemented by the addition of a small amount 

 of the leukocytic extract from the rabbit or guinea-pig, 

 respectively. Furthermore, an inactivated leukocytic 

 extract from a guinea-pig can be activated by the addition 

 of a small amount of the normal serum of a rabbit. (4) 

 Extracts from the polymorphonuclear leukocytes of rabbits, 

 guinea-pigs, and cats destroy in vitro the timothy bacillus, 

 the grass bacillus II, Korn's acid-fast bacillus I, and Rubner's 

 butter bacillus. The extract from rabbits' leukocytes has 

 a bactericidal action on the bacillus tuberculosis of man. 

 Extracts of rabbit, guinea-pig, and cat macrophages do not 

 destroy these acid-fast bacilli in vitro. The same is true of 

 the extracts from the thymus gland of the rabbit. Living 

 polymorphonuclear leukocytes injected into guinea-pigs 

 decrease the virulence of the human tuberculosis bacillus. 

 The leukocytes of the guinea-pig do not have this effect. 

 These experiments do not permit us to draw positive con- 

 clusions concerning the action of living macrophages and 

 lymphocytes on tubercle bacilli, but it appears that rabbit 

 macrophages may have a protective action against these 

 organisms. (5) Extracts from rabbit, guinea-pig, and cat 

 macrophages have no hemolytic effect upon the erythrocytes 

 of chickens, goats, rabbits, or guinea-pigs. 1 



1 This is interesting in view of the statement made by Vaughan (Med. 

 News, December 15 and 22, 1894), from which the following quotation is 

 taken: "On March 19, 1894, I inoculated rabbits 1, 2, 3, 4, 5, 6, a and 

 b with a virulent culture of the (tubercle) bacillus. Animals from 1 to 6 

 inclusive had had previous treatments with a 1 per cent, solution .of nucleinic 

 acid as follows: 



March 9 10 13 14 15 16 17 19 



Amount of solution in 



cubic centimeter . .0.3 0.5 0.6 0.7 1 1 1 1 



a and b had had no nuclein. All of the animals were half-g own, and weighed 

 respectively: No. 1, 714 grams; No. 2, 724 grams; No. 3, 740 grams; No. 

 4, 729 grams; No. 5, 647 grams; No. 6, 614 grams; a, 709 grams; b, 705 

 grams. On July 6, 1894, I killed No. 6, a and 6. No. 6 weighed at this 

 time 1557 grams. I .found a nodule the size of a pea at the point of inocu- 

 lation. In all other respects this animal was normal, I could find no 



