THE SPIROCH.ETES 65 



In 1833 Ehrenberg found the type Spirochseta in 

 muddy pond-water, and described it very briefly 

 indeed. From that time onwards the Spirochceta 

 plicatilis of Ehrenberg seems to have been almost 

 unobserved ; and, even at the present time, there is 

 little evidence that any one of the spirochaete-like 

 organisms of pond - water, recently described as 

 S. plicatilis, is the same as the spirally moving 

 organism seen and depicted by Ehrenberg. 



However, workers after Ehrenberg identified the 

 genus Spirochceta with certain organisms found in 

 sea- water (S. gigantea), and in a blind branch of the 

 gut of the oyster that contains a jelly-like substance, 

 the crystalline style. In 1882, Certes, working on 

 the parasites and commensals of the oyster, wrote a 

 note on the organism, though he called it a trypano- 

 some, while in 1883 Moebius published that he had 

 observed the oyster parasite in 1869. A gap 

 occurred till 1905, when Schaudinn extended the 

 definition of the spirochsetes, for he stated that an 

 undulating membrane should be present along the 

 corkscrew-like body. 



Meanwhile, workers in Tropical Africa had re- 

 corded spirochsetes from the blood of man and 

 mammals, and the study was pushed forward, but 

 beyond increasing the number of species known, 

 little in the way of structural detail was observed 

 until 1906. In that year a paper appeared by 

 Perrin on the parasite of the oyster, which he 

 termed Trypanosoma balbianii, despite the fact that 

 in practically no structural detail did it resemble 

 the trypanosomes, then a relatively well-known 

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