206 



SCIENCE. 



[N. S. Vol. XXIII. No. 580. 



lowed several days later by injection of 

 spiroehsetal blood, has not, in the few ex- 

 periments made, prevented the develop- 

 ment of the infection in rats. 



6. There is no evidence that longitudinal 

 division ever occurs. On the other hand, 

 the constant occurrence of organisms show- 

 ing an extreme attenuation in the central 

 portion, as well as organisms lying end to 

 end, with their pointed extremities in close 

 approximation, strongly indicates trans- 

 verse fission or possibly fragmentation. 

 Long thread-like forms showing several 

 areas of attenuation are seen at times. 



7. No evidence of an enveloping or un- 

 dulating membrane was seen in specimens 

 stained by Wright's, Giemsa's, Prosca's or 

 Loeffler's methods. Likewise no evidence 

 of distinct cilia was obtained. The spiro- 

 chsetes, therefore, more closely resemble the 

 bacteria than protozoa. 



8. In human and rat blood to which has 

 been added sodium citrate to prevent coag- 

 ulation, there can be seen within twenty- 

 four hours after inoculation with a few 

 drops of rat blood containing spiroehsetes, 

 a very evident increase in the number of 

 these organisms. The spiroehsetes are vast- 

 ly more numerous in the smears from the 

 culture fluid than in control smears taken 

 at the time of inoculation, notwithstanding 

 the dilution of infected blood with approxi- 

 mately thirty to fifty times its volume of 

 medium. 



By inoculating several drops of this first 

 generation into a second blood tube, the 

 organism was found in approximately the 

 same numbers in the transplant. A third 

 generation, however, failed to grow. 



Multiplication apparently occurs in the 

 undiluted citrate blood from infected rats, 

 kept overnight at room temperature. More- 

 over, citrated blood, kept at room tempera- 

 ture for six days, retains, unimpaired, its 

 infective properties. 



Spirochwte Obermeieri: P. G. Novy and 



R. S. Knapp, University of Michigan, 



Ann Arbor, Mich. 



The spirochsete studied was obtained 

 through the kindness of Dr. Norris. It 

 has been kept alive by successive passage 

 through white rats for over two months. 

 As a result of intraperitoneal inoculation 

 the parasites appear in the blood in thirty- 

 six to forty-eight hours after inoculation 

 and disappear within twenty-four hours, 

 and do not reappear. The rats are then 

 immune to subsequent inoculation. The 

 disappearance of the spirochetes was shown 

 to be due to the formation of anti-bodies. 

 SpirochiBtal blood when kept in vitro re- 

 tains its virulence for more than fifteen 

 days. 



The blood of rats which have been given 

 repeated injections of spiroehsetal blood 

 exerts a most marked preventive and cura- 

 tive action. "When injections of such blood 

 are made, before inoculation with spiro- 

 chetes, the latter fail to appear. Sim- 

 ilarly, when simultaneous injections of 

 immune and spirochetal blood are made no 

 infection results. Even when the immune 

 blood is injected ten, twenty-five and thirty- 

 six hours after inoculation with spiro- 

 chetes, that is to say, at any time before 

 the spirochetes actually appear in the 

 blood, they will fail to appear, whereas in 

 the controls they become numerous. 



The curative action of the immune blood 

 is equally pronounced. In rats which have 

 from five to ten spirochetes per field of the 

 one-twelfth-inch objective an injection of 

 two cubic centimeters of immune blood is 

 followed within one hour by a total dis- 

 appearance of the spirochetes from the cir- 

 culation (as actually demonstrated before 

 the society). After this the parasites do 

 not appear, while in the controls they per- 

 sist for twenty-four hours. TJiis remark- 

 able euratiye acti9n of immmje blood in th€ 

 case of the white rat will form without 



