koch's comma bacillus. 
47 
One of our chief biologists lias attempted to parody the 
famous joke about the crab, by saying that Koch’s Comma 
Bacillus is so-called (1) because it is not comma-shaped ; (2), 
because it is not a Bacillus. But an inspection of these 
authentic specimens shows that he is wrong in both particu¬ 
lars ; they are curved exactly like a written comma, but of 
course without the distinct head which we see in a printed 
comma. Moreover, they do belong to the genus Bacillus— 
in the Vibrio form it is true, but without the spiral which 
distinguishes the genus Spirillum. It is now well known 
that the members of the old genus Vibrio were of two kinds, 
some merely undulated (Bacillus), some truly spiral (Spirillum). 
For this reason, the word Vibrio is now dropped as a generic 
term. 
Other observers than Koch have met with Bacilli curved 
in a similar comma fashion ; among these one is stated to be 
very common in the mouth of many healthy persons, and 
another has just been discovered by Dr. Deneke, of Gottingen, 
in mouldy cheese. These all present great similarity in their 
form, although differing slightly in their mode of growth in 
nutrient media. But it is obvious that this similarity is no 
proof of identity. There are already numerous instances 
known of Bacilli which, while morphologically almost iden¬ 
tical, are physiologically widely different, e.y ., the hay-bacillus 
and that of splenic fever, the bacillus of glanders and that of 
tubercle. 
Through the kindness of Mr. Sampson Gamgee, of this 
town, my attention has been called to a book just published 
in Italy by Dr. A. Bianclii* containing the observations made 
by the famous Italian physician, Prof. F. Pacini, during the 
cholera epidemic in Florence in 1855. Copies are given of 
drawings of the micro-organisms which Pacini found in the 
bodies of those who died of cholera, made by him at the time, 
thirty years ago, but not published during his lifetime. 
Among these, one which he calls a Vibrio so closely resembles 
Koch’s Comma Bacillus that it can scarcely be doubted that 
Pacini met with the same organism which Koch afterwards 
rediscovered. In one striking point this similarity is most 
convincing ; in Koch’s Bacillus it frequently happens that 
when two curved cells are in contact, end to end, the conca¬ 
vities are turned in opposite directions, thus forming a 
distinct S, and this feature is well represented by Pacini. 
* Nuove Osservazioni Microscopiche sul Col^ra (Milan, 1885), 
p. 4, fig. 2. 
