294 BOTANICAL GAZEITE. | Nov., 
The relative value of cultures in liquid and solid media in the 
diagnoses of bacteria. 
THEOBALD SMITH. 
The marked progress recently made in the study of micro- 
organisms as the cause of certain diseases is without doubt due to 
the more thorough application of various solid culture media 
by Koch and his pupils. Today the microscope does not 
hold the chief place in the study of these minute organisms. It 
is their mode of growth upon gelatine, blood serum, agar-agar, 
potato, in meat infusions, milk, ete., or the absence of growth on 
one or more of these substances and in these fluids which aids in 
confirming the microscopic examination. For this frequently 
yields results so indefinite that without the media mentioned it is 
impossible to come to any satisfactory conclusions as to the kind 
of bacteria under consideration. Besides these various tests, in- 
oculation experiments are of essential importance in the investi- 
gation of pathogenic forms. z 
In connection with the cultivation of bacteria for diagnostic 
purposes, it is again desirable to call attention to liquid media 
and their uses. The statements of Koch and others several years 
ago concerning the unreliability of liquids have almost driven 
them from the field in ermany and in our own country. 
Pasteur, the founder of this new and brilliant branch of path- 
t 
any danger whatever; (2) by frequently testing liquid cultures 
