Jan. 17, 1916 
Plenodomus fuscomaculans 
7 i 5 
under such a range of conditions that accordingly these environmental 
factors have been neglected in culture work. 
The emphasis placed upon nutrition has developed a great body of 
facts regarding media in which organisms will grow and rules for the pre¬ 
paration of the media. These compositions have the common character¬ 
istic that for the most part they present highly concentrated food sup¬ 
plies so complex as to defy analysis. The list includes beef infusion, 
prune juice, wort, Nahr solution, bread (plain or soaked in sugar solu¬ 
tions), vegetables of all kinds, and the long list of nutrient hydrogels. 
These media have given excellent vegetative growth; but if the common 
molds are excluded, it may be said that on the majority of media fructi¬ 
fication is the exception rather than the rule. 
In recent years many kinds of fruits, vegetables, and other biological 
products have been tried, either directly or as a base for a nutrient 
hydrogel. Some of these have produced fructification in forms which 
had previously grown only vegetatively in culture. Notable examples 
are corn meal, or corn-meal agar, which in the hands of Shear (Shear and 
Wood, 1913) and others led to an unraveling of the Gloeosporium com¬ 
plex, and oat agar, which in the hands of Clinton (1911) solved the 
historic Phytophthora infestans difficulty. 
The complexity of the vast majority of combinations used in con¬ 
temporary research, however, does not permit the analysis of the con¬ 
tributing factors which lead to fructification. The net contribution, 
therefore, toward a final analysis, which would furnish a key for unlocking 
closed approaches with other organisms is small, and further advance, so 
far as indicated by such work, must be by the same wasteful method of 
haphazard trial. It is known that organisms will grow under a vast 
assortment of conditions, but very little is known of the conditions 
which call out any particular phase of development. 
Our knowledge of the physiology of micro-organisms has largely come 
from a study of their behavior under controlled conditions. The very 
analytical nature of the type of research used in the study of metabolism 
has made its methods in sharp contrast with those just described and 
has made possible evaluation of the various factors involved. The pure- 
culture methods just discussed and researches on the metabolism of 
micro-organisms have progressed side by side, and only slightly have the 
basic principles of the latter been influential in determining the course of 
the former. The art of cultivating organisms has indeed been developed, 
but this work is almost wholly empiric; although there is a mass of funda¬ 
mental facts dealing with metabolism and with the reactions of plants 
to their environment, these for the most part are totally ignored in ordi¬ 
nary culture methods (Benecke, 1904; Behrens, 1904, p. 436-466). 
Studies of the effects of various factors upon the metabolism of fungi 
naturally were made first with the nutrition of the micro-organisms. 
It was essential that the work be done with synthetic media; and along 
