ANIMAL MICRO-PARASITES. 595 



relapsing fever, closely resembling relapsing fever in man. At the 

 same time it is worth recording that^ until Steel observed the 

 presence of the parasite described by Evans he regarded the out- 

 break as malarious in origin, and provisionally termed it gastric 

 typhoid. In the Burma outbreak, as in the Punjab - epidemic, 

 considerable evidence was adduced in favour of regarding the disease 

 as being due to bad water supply. 



Steel succeeded in staining the organism with aniline dyes, but 

 bis description of the parasite in the fresh state differs very 

 materially from that given by Evans. 



Steel failed to recognise the round , body tapering in front to a 

 neck. To him the bodies appeared thick in the middle, gradually 

 diminishing in size in either direction, with a blunt and rigid 

 extremity at one end. The opposite end he described as tapering 

 in such a way as to produce a subspiral prolongation, which was 

 uncurled and lashed about freely like a whip. This tail was 

 •described as slender in relation to the general size of the parasite ; 

 but under the highest power available the presence of a colourless 

 flagellum could not be detected, nor, he adds, did the movements of 

 the blood-constituents indicate its existence. ' 



Steel also failed to see the slightest sign of the two fin-like papillae 

 on each side as described by Evans — an opinion in which he was 

 supported by Lewis. 



These two observers, Evans and Steel, also differed as to whether 

 the movement could be called spiral. Steel felt convinced that their 

 movement was as much of that nature at times as can be expected 

 from organisms with so open a corkscrew shape ; while Evans 

 maintained an opposite view. In the dried and stained specimens 

 Steel observed that they retained their subspiral form of body and 

 markedly spiral form of tail. 



Steel found that the disease coUld be communicated to the dog 

 and to the monkey, and then discussed the resemblance of the parasite 

 to the spirillum of relapsing fever in man. 



From the different appearances presented by the parasite when 

 in the living state and when dried and stained. Steel thought that 

 there was probably a still closer resemblance to the living spirillum 

 than to the dried and stained one, and argued that the figures of 

 spirilla like corkscrews must be purely imaginary. Steel, it 

 must be observed, founded these remarks upon figures in text- 

 books, and not on photographs or on a practical acquaintance 

 with the spirillum of relapsing fever. One cannot refrain from 

 pointing out the value of photomicrographs, for they cannot be 



