GENERAL CHARACTERS OF SPIROCH^TES. 



47 



immunity against this parasite, but not against Sp. 

 obermeieri; and agglutination tests also point to a 

 specific difference between the two spirochaetes. Mice 

 and guinea-pigs can be inoculated with this organism, 

 as can also rabbits, horses and monkeys. The patho- 

 logical changes seen after death are the same as in 

 infection with Sp. obermeieri. The spirochaetes are taken 

 up by the ticks from the blood of an infected person 

 and are passed on in the egg to the young ticks of a 

 second generation. Koch describes filamentary forms 

 of the spirochaete in these animals. Levaditi and 

 Manou^lian believe that destruction of the spirochaete 

 and cure of the disease are brought about by phagocy- 

 tosis; some of the symptoms of the malady are attrib- 

 uted by them to thrombosis of blood-vessels caused 

 by impaction of masses of spirochaetes. 



OTHER FORMS OF RECURRENT FEVERS. 



Relapsing fever as seen in America is said to be caused 

 by yet another spirochaete. Schellack gives the follow- 

 ing description of the three allied organisms: 



It is not impossible that other species may be 

 found to exist in different parts of the world where 

 forms of relapsing fever are encountered. Thus the 



