126 THE ANIMAL PARASITES OF MAN 



provides a special form of nourishment. At first T. pallidum grows in 

 the solid medium, and then when the cultural conditions in the lower 

 fluid portion become favourable, the organisms migrate thither and 

 multiply abundantly. At first the culture is impure, but after several 

 transferences a pure culture is obtained readily. 



The syphilitic material for culture is prepared by cutting off 

 pieces of tissue from the lesions, washing in sterile salt solution 

 containing i per cent, sodium citrate, and then emulsifying the 

 tissue in a mortar with sodium citrate. 



Good cultures show rapid multiplication, which is invariably 

 by longitudinal division. 



In his various cultivation experiments Noguchi 1 found morpho- 

 logical and pathogenic variations in T. pallidum. Three forms of the 

 organism were found, namely, thicker, average and thinner types. 

 The lesions caused in the testicle of the rabbit differ according to 

 the variety inoculated, but more work is necessary on the subject. 



Noguchi 2 has cultivated a separate organism, T. calligyntm, 

 from the surface of human genital or anal lesions, either syphilitic 

 or non-syphilitic. It is apparently non-pathogenic, and is 6 //, to 

 14 p long. 



Hata(i9i3) 3 has modified the Noguchi technique for the cultivation 

 of spirochaetes and treponemes, with a view to simplification and 

 convenience. Hata substitutes normal horse serum for ascitic fluid 

 and the " buffy coat" of the clot of horse blood in place of the small 

 pieces of rabbit's kidney. It is unnecessary to place sterile paraffin on 

 the surface of the medium. 



The horse serum is mixed with twice its volume of physiological 

 saline solution. The mixture is placed in tubes which are heated on a 

 water-bath at 58 C., the temperature being raised gradually until it 

 reaches 70 or 71 C. in three hours. The tubes are then heated at 

 71 C. for half an hour. After cooling, the contents will consist of an 

 opaque semi-coagulated mass. This semi-coagulated serum and saline 

 mixture may be substituted for Noguchi's ascitic fluid. 



The buff coagulum is cut into small pieces, about i c.c. in volume* 

 They must be forced with a sterile glass rod to the bottom of the semi- 

 coagulated serum and saline mixture. The medium is inoculated with 

 a small quantity of infected blood and kept at 37 C. In the case of 

 S. recurrentis, growth of spirochaetes is observed on the second day, 

 reaching a maximum in five to seven days. The growth of the 

 organisms proceeds rather more slowly, they live for a longer period 

 and maintain their virulence better than in Noguchi's medium. 



1 [ourn. Exptl. Med., xv, p. 201. 2 fourn. Exptl. Med., xvii, p. 89. 



3 Centralbl.f. Bakt., Orig., Ixxii, p. 107. 



