RECENT RESEARCHES INTO THE HISTORY OF BACTERIA. 2!f3 



speimatozoa of vertebrates, and rapidly increase in number; 

 these are clearly either Heterocysts, or, as is more probable, 

 spores, which belong to the life-history of Bacillus, and are 

 produced under certain conditions. If this be so, Bastian's 

 experiments are explained, for the spores were able to resist 

 the comparatively short boiling to which they were subjected, 

 and easily grew to maturity in the nutritive fluid in which 

 they found themselves. In many other cases Cohn says he 

 has observed such lasting spores; and lest some one, tempted 

 by peas instead of cheese, should feel inclined to write two 

 volumes on the ' Beginnings of Life,' it had better at 

 once be added, that a similar putrefaction was observed in a 

 solution of peas in distilled water, ivhich had been kept for 

 several days at 45° C. 



25. Spirochete Obermieri is already known to English 

 pathologists from Dr. Burdon Sanderson^s Report on the 

 Pathology of Infective Processes,^ where he figures, from a 

 drawing sent by Cohn, the '^ spirillum" of relapsing fever. 

 So full an account is there given, that it will be here suffi- 

 cient to add what Cohn has since discovered concerning 

 these organisms. They do not belong to Spirillum, but to 

 the genus Spirochcete, of which only one species, S. plicatilis, 

 has been hitherto known ; and that, thanks to the labours of 

 Ehrenberg, who, like Cohn, found it in the water of marshes. 

 This latter differs from Spirillum in the character of its move- 

 ments, which are at times serpentine ; the screw-like wind- 

 ings of the fibres are constant in character, but their length 

 is most variable. In addition to the serpentine movements, 

 by which they are enabled to change their place, they also 

 exhibit an undulation passing along their whole length, 

 which has never been observed in Spirillum. Cohn is unable 

 to say whether the form found in the blood is the same as 

 that which is found in marshy water ; if so, it is quite pos- 

 sible that the fever was produced by drinking it ; another 

 Spirochsete, how^ever, was once observed by Cohn in the 

 mucus of his own mouth, which appears to be intermediate 

 between these other two forms. 



It may be added that osmic acid, as Weigert has shown, 

 preserves their characters unchanged. 



26. The [bacterium of splenic fever was also cited by 

 Dr. Burdon Sanderson;^ Cohn now gives it the name of 

 Bacillus Anthracis, which differs from the Bacillus of butyric 

 fermentation {B. subtilis), in being shorter and firmer, and 



> Report of Medical Officer of the Privy Council, &c., N. S., No. Ill, 

 1874, p. 41. 

 2 loc. cit., p. 35. 

 VOL. XVI.— --NEW SER, S 



