378 ABSTRACTS 



and the small number of cases examined, the work does not appear 

 to be conclusive. — H. W. L. 



The Etiology of Rocky Mountain Spotted Fever. S. B, Wolbach, 



(Jour. Med. Res., 1916, 34, 121-127.) 



Guinea-pigs inoculated by ticks infected with the virus of spotted 

 fever, show definite pathological changes characteristic of this disease. 

 The author finds in the diseased tissue an organism, agreeing in most 

 respects with that of Ricketts, which he feels justified in calling a bacil- 

 lus. This organism is described as Gram-negative, resembling some- 

 what B. influenzae but stained bluish by Giemsa, in contrast to most 

 bacteria. All attempts to cultivate the organism have failed. 



H. W. L. 



Studies on Treponema pallidum and Syphilis. II. Spirochaeticidal 

 Antibodies against Treponema pallidum. H. Zinsser, and J. G. 

 Hopkins. (Jour. Exp. Med., 1916, 23, 323-328.) 

 Cultures of the Treponema were grown on a new medium consist- 

 ing of inspissated egg in tubes filled with broth serum mixtures. This 

 method makes it possible to obtain clean antigen, unmixed with tissues 

 detritus, a disadvantage incident to tissue cultures. The authors 

 believe that their experiments have shown that the serum of rabbits 

 and sheep immunized with cultures of Treponema pallidum acquire 

 spirochaeticidal properties for these culture spirochaetes. The normal 

 serum of these animals also possesses spirochaeticidal action if used 

 in sufficient quantities, and the action of the immune serum repre- 

 sents probably an increase of normal antibodies. Both normal and 

 immune spirochaeticidal properties are destroyed by heating to 56°C. 

 but the serum can be reactivated by the addition of fresh normal serum of 

 the same species, insufficient in amount to exert a spirochaeticidal effect 

 by itself. The structure of these spirochaeticidal bodies appears to 

 be analogous to that of the well-known bactericidal antibodies known 

 to exist in antibacterial sera. It is pointed out by the authors that 

 these results apply to culture spirochaetes. — G. B. W. 



III. The Individual Fluctuations in Virulence and Comparative Viru- 

 lence of Treponema pallidum Strains Passed Through Rabbits. Hans 

 Zinsser, J. G. Hopkins, and M. McBurney. (Jour. Exp. Med., 

 1916, 23, 329-340.) 



Rabbits were inoculated with strains from human cases with the 

 purpose of studying differences in racial and acquired virulence. The 

 authors found no difference in pathogenicity between the different 

 strains, although they were isolated from various lesions, and, further, 

 these strains show no consistent change in rabbit pathogenicity dur- 

 ing progressive rabbit passage (21 generations in one case). Variations 

 in the lesions produced, and also in the incubation time are probably 

 due to variations in technique. — G. B. W. 



