754 
Journal of Agricultural Research 
Vol. V. No. 16 
we have in these complex forms the same sort of result as was obtained 
in Table XXIII. But, in spite of the variety, the growth is much the 
same, and when fruiting bodies are produced they are the same mor¬ 
phologically. Such uniformity can be explained only by the assumption 
of an assimilation process which deals with much the same stuffs in all 
the substrata. The reserve materials are then worked over by the pro¬ 
toplasm under favorable conditions, and the fructification takes place. 
Effect op Change of Intensity of a Factor during the Growing Period 
Those experiments of Klebs (1899) in which a bit of rapidly growing 
mycelium of Saprolegnia mixta was transferred from a good nutrient 
solution to another of poorer quality, with resulting strong response in 
sporangium production, are the most striking demonstrations of the 
relation of checked growth to reproductive processes. In experiments 
of this type we have a device for studying some of the factors with the 
aim of their further simplification. We must, however, recognize that, 
no matter how ingeniously the term “checked growth’” fits the phe¬ 
nomena described, it really tells us little about the physiological pro¬ 
cesses underlying. 
The following experiment was performed. Strongly growing mycelium 
(1 week old on com broth) was washed in two changes of 500 c. c. each of 
conductivity water. This mycelium was cut in pieces approximately 
the same size with sterile scissors and was added to the various sterile 
solutions shown in the table, with the results shown in Table XXVI. 
TabuE XXVI —Effect of change of intensity of a factor: Withdrawal of food supply 
[Time, i -week] 
Medium. 
Number of 
pycnidia. 
Growth in¬ 
crement. 
i-week-old mycelium added to— 
Filter paper. 
25 
f 
++ 
++ 
++++ 
+ 
+++++ 
++ 
++ 
Conductivity water. 
Com broth, 1/40. 
D 
25 
O 
Com broth 1X. 
Magnesium sulphate, approximately Mjioo . 
2 
Pea broth. .. 
O 
Pea broth, 1/40. 
O 
Check (similar mycelium allowed to grow undisturbed).. 
0 
It is evident from these results that with the withdrawal of the food 
supply from vigorous, susceptible mycelium reproduction sets in promptly. 
The results were obtained in one week—two weeks after inoculation— 
although normally pycnidium production with com grains is much slower. 
This hastening of the reproductive process by change of quantity of food 
supply indicates that here we were able to produce the change which 
takes place more slowly in the ordinary cultures. 
