NOTES AND MEMORANDA, 653 
and then makes a long shallow streak with the needle’s 
point upon the surface of the gelatine. The Bacteria which 
were adhering to the needle’s point are in this way dropped 
at intervals along the streak, some nearer some further 
apart, but all (with rare exceptions) in such a way that 
their subsequent growth keeps clear of that of a neighbour, 
and can, with the aid of a low power or even without any 
microscope, be visited by a sterilized needle point, and thus 
used to start on another gelatine plate a perfectly pure cul- 
tivation. 
These pure cultivations, such as Lister aimed at by his 
method of dilution and division, may be called, in order to 
indicate to what an extent they are known to be pure, 
*‘monosporous cultivations,” since the principle which dis- 
tinguishes them is that all the growth is the offspring of a 
single isolated germ or spore. 
It is only by such monosporous cultivations that we can 
arrive at solid conclusions in reference to the forms and 
activities of the Bacteria, e.g. as to whether one form can 
give rise to progeny of another form when its food and con- 
ditions of growth are changed, and again, as to whether 
special fermentative powers can be lost or acquired in the 
course of generations derived from one parent germ, but 
subjected to different conditions as to food, temperature, and 
oxygen. 
The method of gelatine cultivation devised by Dr. Koch, 
places the means of following out these inquiries in the 
hands of every careful microscopist. Such methods as 
Lister’s were too troublesome and too difficult for general 
and widespread application; but now that monosporous 
cultivation of Bacteria has been rendered a comparatively 
simple and certain affair, we may expect immediate and 
immense advances in our knowledge of the whole series 
of phenomena to which the Bacteria are related. 
Amongst problems which require immediate investigation 
by the new method are the distinctive properties of the various 
kinds of Bacteria which may infest the wounds of surgical 
practice, and their specific susceptibility to the destructive 
influence of carbolic acid and other antiseptics ; further, the 
possibility of isolating a specific Bacterium in contagious 
diseases not yet investigated: and (of great physiological 
interest) the isolation and investigation of the properties 
of the specific Bacterium of the ammoniacal fermentation of 
urine. 
Dr. Koch and his assistants will, no doubt, shortly publish 
a detailed account of the researches which they have been 
