Page:Researches on Irritability of Plants.djvu/126

Rh former position. If the temperature be raised again, there is once more a growing erection, and when the death-point is reached there is a sudden spasmodic contraction.

But if the specimen once passes through the temperature at which the spasm takes place, then there should be an abolition of all further response, proving the sudden contraction at 60° C. to be the spasm of death. Thus, after obtaining the sudden inversion of the curve at 60° C. in the last experiment, the plant was kept at that temperature for 15 minutes. Cold water was now substituted in the bath, and the record was taken once more of the effect of rise

and fall of temperature. A record is reproduced (fig. 59) which exhibits the result. In the lower curve is shown the record of effect of rise of temperature from 45° to 65° C., and in the upper the effect of cooling from 60° to 45° C. It is seen that while in the last experiment the plant exhibited a spasmodic contraction at 60° C., there is no trace of such an effect in the present case. The very slight movement observable in the two curves is the physical effect of heating and cooling, quite negligible compared with the physiological erectile movement due to warming and the subsequent spasmodic contractile movement heralding the initiation of death-change.