Marks , employed for classifying the Schizomycetes. 1 3 7 
The fact which militates most distinctly against the latter 
view is that there is no evident correspondence between the 
numbers of the forms in the three different media. But, on 
the other hand, there is experimental evidence to show that a 
form which grows like an ordinary Bacillus in a saccharine 
medium may look very different if cultivated in beef-broth, 
and so on. Such facts should make us very circumspect in 
dealing with such cases as mixed cultures. 
The case is different, however, when we are deciding as to 
the identity or distinctness of two pure cultures. If we find 
that, other circumstances being equal, one of the forms will 
grow readily on gelatine, but the other will not, then the 
conclusion is justified that they are distinct: the converse is 
not true, however. It may be remarked here that a close 
examination of the literature shows abundantly that many 
bad records are due to negligence of these, now obvious, pre- 
cautions that all the circumstances of comparison should be 
equal, including even the apparently trivial, but really impor- 
tant one, that the nutritive gelatine, broth, or other medium, 
should be of the same stock and make. 
Having once 6 run a form down 5 to this point, it is pretty 
clear that MiqueTs further characters — the importance of 
which has been recognised more and more since cultivation 
on solid media was introduced by Brefeld and Koch — are both 
distinctive and, on the whole, easy of application. The colour 
and shape of the colonies, the liquefaction of the gelatine, the 
formation of scums, production of pigments, the shape of the 
cells and their mode of aggregation, and so forth, are all 
points comparatively easy to observe, and their utility needs 
no comment. 
It is pretty clear then that a scheme like this of Miquel’s, if 
properly and consistently applied, is calculated to perform two 
great functions in advancing our knowledge of Schizomycetes. 
In the first place, it satisfies the subsidiary requirements of 
the specialist who merely wants to e spot ’ a given form, and, 
as said, we are not concerned in criticising the desirability of 
that object. 
