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XX. — On the Cholera " Comma " Bacillus. 

 By G. F. DowDEswELL, M.A., F.R.M.S., F.L.S., &c. 



CRead Uth October, 1885.) 



The circumstances of tlie discovery of the so-termed cholera 

 " comma " bacillus, by Dr. Koch, with the question of its relation 

 to the disease in which it occurs, are so generally known that it 

 is not necessary to recapitulate them here. 



Since I first showed preparations of the microbe to this Society, 

 some months ago, it has been the subject of increased attention 

 and interest from the account of the investigations of Dr. Klein 

 and the English Cholera Commission in India, whose conclusions 

 on the point which in this subject is of paramount importance — viz. 

 the setiological relations of the microbe to disease — are directly 

 subversive of the view which was somewhat generally accepted 

 previously, on the authority of Dr. Koch. This interest too has 

 been still further increased by the terrible devastation that is being 

 w orked by this disease on the continent of Europe, and immediately 

 threatening our own country. I now offer to your notice what I 

 have myself observed of the characters of this organism, and which 

 from a purely mycological and microscopical point of view, render 

 it one of the most interesting and remarkable yet described. 



In the classification of Cohn this microbe is a SjnriUum, the 

 mature cells showing the character of that by no means well- 

 known genus ; the ordinary singly-curved, or so-termed comma- 

 form, being evidently an early stage of development of the species. 

 It is here somewhat variable in form and size in different con- 

 ditions of nutrition, the composition of the cultivating medium, and 

 other circumstances. 



In a certain stage of development the cells are frequently so 

 strongly curved as to form the distinct segment of a circle ; in the 

 earlier stages less so ; it never, however, forms perfectly straight 

 rods of any size, nor can be mistaken for a true Bacillus, though 

 in any preparation a few cells may, to a superficial view, appear 

 straight, as when a disc or circle is viewed edgewise. From the 

 typical so-termed " comma " shape it assumes a sigmoid or sinuous 

 form ; some of these at first were rather difficult to understand ; in 

 many cases no doubt the somewhat frequent V-shaped form may be 

 due to incipient fission of the cell which occurs largely at this 

 stage ; in others it is but the first coil or turn of the spiral, which 

 is its mature form, but which is by no means attained by every 

 individual cell or in every cultivation. These mature Spirilla, in 

 natural or undried preparations, are very beautiful objects, the coils 

 of the helix which, when dried, are generally flattened and distorted, 



