104 Marshall Ward . — On the Characters , 
has unconsciously heaped up an immense store of trouble for 
the new type of bacteriologist which the needs of the times 
are bringing forward. The trouble has arisen quite naturally, 
owing to the two sets of observers having had their backs 
turned to one another, and their attention concentrated along 
different avenues of research. Let us look for a moment at 
the kinds of characters that each has brought into the fore- 
ground, and then try to make out from the work of the few 
who are now turning round as they work (so to speak) and 
looking at each other's efforts with scientifically sympathetic 
eyes. Since it is not my object to write a history of 
bacteriology, I pass over the work of the earlier observers 
Leeuwenhoek, Will, O. F. Muller, Bory de St. Vincent, Spal- 
lanzani, Ehrenberg, Dujardin. Pertz, Hallier, Burdon-Sanderson, 
Pasteur, and others, simply reminding my readers that many 
very interesting facts had been recorded, and even classifi- 
cations of micro-organisms constructed, long before Cohn’s 
time. 
The school which culminated in the brilliant efforts of 
Cohn was almost entirely concerned with the preparation of 
the ground on which the subsequent struggles were fought, 
and from which the new departures were taken. 
Ehrenberg, Kiitzing, Rabenhorst, Schroter, Warming, 
Cohn, and others had recorded, prior to 1880, a considerable 
number of forms of Bacteria of various kinds. For the most 
part these records were records of * finds 3 : that is to say, 
each observer overhauled the contents of the ponds, aquaria, 
macerating-troughs, and so on, at his disposal, and faithfully 
delineated the forms of the organisms found therein, named 
them, and added the habitat, &c. The method was the 
usual one of an exploring botanist in a new country, and 
quite properly so. The results began to take a modern shape 
under the hands of Cohn, who, in 1872 and 1875, brought 
forward his long celebrated system of classification of these 
organisms, based almost entirely on their forms as found and 
recorded ; though, at the same time, I think Cohn was more 
alive to the imperfections and tentative character of his 
