SPIROCHAETOSIS 493 



probably a distinct species (L. tropica). On cultivation 

 it develops a flagellated form. The disease has a seasonal 

 prevalence, and Wenyon suggests that it is conveyed by 

 a mosquito, a species of Stegomyia. 



In N. Africa Nicolle has observed a Leishmaniosis of 

 children due to another species (L. infantum). It is trans- 

 missible to the dog and monkey, and can be cultivated. 

 The disease has recently been found all along the Mediter- 

 ranean littoral. 



Spirochaetosis l 



Diseases caused by infection with spirochaetes. The spirochaetae 

 are delicate, undulating, or somewhat spirillar, filiform parasites 

 occurring in the blood of man, mammals, birds, shell-fish, etc. The 

 filaments taper to a point at the ends, are flexible and motile, 

 coiling and uncoiling, are described as having two nuclear masses, 

 and some possess an undulating membrane, like trypanosomes, 

 but in the smaller forms no definite structure can be made out. 

 They are now generally regarded as protozoa, but some still con- 

 sider them to be bacteria. Bacterial cells are never pointed, nor 

 do they show the coiling movements of spirochaetes ; motility is 

 produced by flagella, which are absent from most spirochaetes 

 (statements to the contrary are due to errors of observation and 

 technique), and periodicity is not exhibited by bacteria. Spiro- 

 chaetes are said to multiply by longitudinal fission, while fission 

 in bacteria is transverse (Dobell states that multiplication is always 

 by transverse, but multiple, fission. See p. 12) ; they react in 

 some cases to drugs (e.g. salvarsan) like trypanosomes, are much 

 more sensitive to the action of immune sera than bacteria are, and 

 are transmitted by insects. Noguchi has cultivated certain spiro- 

 chaetes of the mouth and relapsing fever by a method similar to 

 that which he employed for syphilis (p. 497). For the saprophytic 

 spirochaetes a small quantity of oxygen is required, for the blood 

 spirochaetes absolute anaerobiosis is necessary as in the case of 

 syphilis. 



Schaudinn believed that many so-called spirochaetes may be 

 connected with the trypanosomes. In 8. plicatilis he described 

 the presence of a thread-like nucleus and of chromidia, and of 

 an undulating membrane, but flagella are absent. In the little 



1 See Nuttall, Jaurn. Roy. Inst. Pub. Health, xvi, 1908, p. 449. 



