101 



tible influence si tfe dumber -of eonidia, 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 w r ith 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 



FIG. 4. Tri-pointed conidia of I H. No. 

 23 and H. No. 36 (see text. p. 102). 



