101 
tible influence on the number of conidia, though as it approached corn-meal 
agar conidia-production became profuse. 
NUTRIENTS AS AFFECTING CONIDIAL LENGTH, SEPTATION, AND SHAPE 
Plates of washed agar when solid were inoculated with H. No. 1, and 
when the colony had grown to a diameter of about 3 cm. one of various 
nutrients was laid on the agar in approximately equal volume, at a distance 
of 1 cm. from the edge of the colony. When growth had ceased, graphs of 
conidial length were made. These graphs, with data sufficiently explana- 
tory, are given in Fig. H. While the number of measurements made is too 
small to warrant any definite conclusion as to nutritive values, the obvious 
general conclusion is that the added nutrient did markedly affect conidial 
length. It is particularly noticeable that washed agar plus saccharose, 
tapioca, or rice gave small conidia, and in none of these cases was modal 
conidial-length equal to that of conidia grown under standard conditions 
(see Fig. K). Even the very striking modification represented by the bi- 
modal curve shown in Fig. I was a product of environmental change. It 
was noted in the sample from which the graph was plotted that the conidia 
were produced in rather large clusters, the oldest one being largest, the others 
mostly much smaller. The minor mode here apparently represents conidia 
in a stage of arrested development, comparable with those of Graph 62 
(Fig. O), while the major mode stands for conidia that approached more 
nearly to normal development but did not attain full size (cf. graphs of 
Figs. I and O with those of Fig. K). That the bimodality is not due to 
Fic. 4.—Tri-pointed conidia off H. No. 
23 and H. No. 36 (see text, p. 102). 
