368 True -—On the Influence of Sudden Changes of 
magnitude of this minimal difference varies according to the 
properties of the membrane and of the protoplast. 
From the above cited investigations, it seems that two kinds 
of results have been found to follow sudden changes of con- 
centration. In the rupture of cell-membranes seen in the 
moulds and Algae, we have extreme cases of the mechanical 
effect of a sudden increase of turgor. 
In the Myxomycetes, in which those tensions arising from 
the presence of a cell-membrane are done away with, we find 
the protoplasm free to respond by means of irritation move- 
ments. That, in the cellular plants, also, results due to the 
irritable nature of the protoplasm may likewise be present, 
but obscured more or less by the striking physical phenomena, 
is not to be forgotten. It would, indeed, seem probable that 
such is the case. It would, furthermore, be expected that 
these irritation-modifications would, in one way or another, 
find expression in the growth-rate, since this is the resultant 
of so many factors, and is, in so many directions, open to 
change-producing influences. The evidence bearing on this 
point is very incomplete. Oltmanns 1 and Eschenhagen 2 
found a decreased rate of growth to follow sudden changes of 
the concentration of the substratum, but no systematic measure- 
ments show the extent or duration of such retardation. 
Materials and Methods. 
For the purposes of this investigation, the radicles of young 
seedlings were selected as the most desirable objects ; and, 
owing to their superior ability to withstand the hard con- 
ditions necessarily offered in these experiments, those of 
Vicia Faba were generally used. Pisum sativum and Lupinus 
albus were used as objects for comparison. The seeds were 
soaked in water until swelled, and for further germination 
were placed in sawdust and kept at the ordinary room-tem- 
perature. After 40 to 45 hours, when the radicles were from 
17 to 35 mm. long, they were ready for use. In the investi- 
1 Oltmanns, loc. cit., p. 194. 
2 Eschenhagen, loc. cit., p. 35. 
