Notes. 
657 
Colour-variations have long been known. I have confirmed the 
occurrence of white varieties of crimson forms, and find considerable 
variations in yellow pigmented forms. An interesting case is that of 
white varieties of a violet Bacillus , so permanent that I have cultivated it 
for weeks and even months as a white form, and can only get it to pro- 
duce its pigment in broth, though otherwise it seems vigorous enough. 
In view of these and other results, which I hope to publish later, it 
seems extremely probable that the following three propositions are true. 
(1) That variations in the form, rate of growth, size and colour, and 
other characters of plate-colonies result from much slighter variations in 
the gelatine and other environment than has hitherto been recognized. 
(2) That, regarding the water of a river as the food-medium, the 
vicissitudes which a Bacillus has been exposed to in this medium 
previous to its capture and isolation in the laboratory, may have 
stamped on it such differences that its plate-colonies differ considerably 
at different times of the year, or even in the same season according to 
the length o'f time the individual germ isolated has been in the river. 
(3) It is in great part owing to the coincidence of these causes of 
variation that it is often so difficult to recognize a given ‘ species' 
described in Eisenberg and other authorities: in fact, the same 
‘species’ recurs under different names, because the conditions preceding 
and during its cultivation in the laboratory have differed more or less. 
The only way out of this difficulty will be, I think, to cultivate each 
form from the begining for a sufficiently long period under conditions 
as accurately known as possible, and strictly according to some care- 
fully arranged plan agreed on by bacteriologists in council beforehand. 
H. MARSHALL WARD. 
A FALSE BACTERIUM 1 . — During my investigations of the 
bacterial flora of the Thames, a form has turned up which well 
illustrates the truth that the methods of tube-plate-cultures of minute 
organisms may lead one astray, and that in order to settle the question 
of the nature of such forms we must employ the methods of direct 
cultivation from a single germ under powers of the microscope : that, 
in fact, we must supplement the macroscopic gelatine-plate-cultures of 
Koch and his followers by the original microscopic gelatine-cultures of 
Klebs, Brefeld, and De Bary, which preceded and suggested the now 
usual methods. 
1 Read before the Botanical Section of the British Association at Ipswich. 
