Turgor and of Temperature on Growth . 397 
during the ensuing quarter hour. Further effects plainly due 
to the change are not to be traced in the later growth. It 
increases or diminishes according to the internal conditions 
prevailing. The transfer from 18 0 to 30° is always followed 
by an increased amount of elongation during the ensuing 
35 minutes. As before, the growth-rate gives no further evi- 
dence of being influenced by the temperature-change. In 
both cases, the traceable effects of the change disappear within 
15 minutes. 
By subtracting the growth made during the period following 
a temperature-change from that made during the period pre- 
ceding the change, we get the amount of retardation or of 
elongation due to the change. To be sure, an uncertain factor 
in every case is the possible change in the rate of growth due 
to internal stimuli, and the results obtained can perhaps hardly 
be regarded as the pure effect of the act of temperature- 
change. This source of error is, however, not to be avoided. 
The amount of retardation so calculated, following the sudden 
transfer from 30° to 18 0 , is rather variable, as would, indeed, 
be expected, and depends somewhat on the rate of growth 
prevailing at the time of the change. The average retardation 
calculated from a number of experiments is 0-08 mm. The 
growth during the following period is usually equal to the 
average found at the temperature in question. On making 
the reverse change, the acceleration of the rate of elongation 
called forth during the period following is likewise rather 
variable, but averages o-n mm. Here again the succeeding 
growth is usually characteristic for the higher temperature. 
In both cases the growth-rate of the new temperature seems 
to be immediately assumed. This receives further attention 
below. 
The phenomena of contraction and of elongation seen 
immediately after a sudden temperature-change between 
extremes more widely separated, as well also as the suc- 
ceeding retardation of the growth, seem to call for a closer 
examination. 
• A sudden fall of temperature, as we have seen, produces 
F f 
