•274 
Sjnrochaetosis 
it is best to collect the infected blood at the 48th to the 72nd hour of 
the disease, and the tubes should be maintained at 36° C. He experi¬ 
mented with S. duttoni and two strains of S. recurrentis which he calls 
kochi and ohermeieri. S. duttoni was still virulent after the 9th trans¬ 
plantation ; S. kochi was transplanted 29 times, subcultures being made 
every four to nine days, the maximum growth being attained about the 
9th day. This strain appeared to lose its virulence by prolonged culture. 
S. ohermeieri attained its maximum growth on the 7th day, and was still 
virulent after having attained the 7th subculture. 
To sum up, then, we have represented in the blood-inhabiting spiro- 
chaetes of warm-blooded animals a group of microorganisms which, under 
natural conditions, are mainly conveyed by blood-sucking ectoparasites 
within which they undergo a process of development and in which they 
are hereditarily transmitted. Spirochaetes are not specialized parasites. 
Infection may take place through the .skin or mucous membrane to 
which the spirochaetes gain access by being deposited thereon in the 
arthropod’s dejecta or by the infested individual scratching or rubbing 
himself with hands which have become contaminated with the contents 
of the vermin which they have crushed. The lesions produced by the 
bites of the arthropods and the excoriations inflicted upon the individual 
by himself greatly facilitate the entrance of the spirochaetes. 
