174 



PLANT RESPONSE 



a tabular statement which makes it possible to see at a 

 glance how concordant these results are. 



Table showing Death-points obtained by different Methods 



Specimens 



1-6 



7-10 



11-14 



i5- 



16. 



17- 

 18. 

 19. 



1 Coronal filament of Passiflora . 

 1 [Six specimens used. Each gave 

 [Style of HiHscm 



l [Four specimens. Each gave] 



1 Style of Datura 



I [Four specimens. Each gave] 

 Pulvinus of Mimosa. Young 

 Spiral tendril of Passilora 

 Peduncle of Allium. Young 

 Flower of French Marigold 

 Flower of Ipomcea . 



Method 



Morograph. 



Spasmodic lateral movement. 

 Movement of uncurling. 

 Expulsion of contained water. 

 Opening or closing of flower. 



Death- 

 point 



C. 



6o° 



6o° 



6o° 

 59°-6o° 

 59° 

 59° 

 59° 

 62 



It will thus be seen that, using very diverse methods and 

 specimens, we nevertheless always obtain a death-point which 

 is very near 6o° C. 



Summary 



In radial organs, the death-contraction due to heat- 

 rio-or is abrupt, and takes place at a definite temperature, 

 which is to be regarded as the death-point. 



In the thermo-mechanical curve given by the Morograph, 

 the point of inversion is the death-point. 



When death has taken place, a repetition of the experi- 

 ment shows no inversion. 



The death-point, due to heat-rigor, in phanerogamous 

 plants, under normal conditions, is found, though obtained 

 by various methods, to be very close on 6o° C. 



Under the action of continuous lowering of temperature 

 there is produced, at a definite minimum degree, a spasmodic 

 contraction, due to cold-rigor. 



The death-contraction in plants is in every respect 

 similar to the same phenomenon in the animal, and is an 

 instance of true excitatory effect. As in the animal, so also 



