Hydration and Growth of Colloids and Cell-masses. 



125 



chamber, where the water in which they were immersed was raised 

 to 28° C. and kept at that point for 40 Jiours. Increased imbibition 

 ensued, which resulted in an elongation of 1 mm. or 8 per cent of their 

 total height. Measurements of the growth of leaves arising from the 

 apices of such corms showed that they maintained a rate of about 0.25 

 mm. per hour at air-temperatures of 19° C, which was increased to 0.49 

 mm. per hour at 27° to 28° C; the temperature coefficient of such 

 elongation would thus be nearly 2.5. 



A second pair of preparations with young leaves about 10 to 12 cm. 

 long was placed in a small, well-lighted thermostat, and the apices of 

 the second or younger leaf were attached to the auxographs. The 

 action of these plants was followed for a period of about 20 days, 

 during which time the leaves reached a length of 25 to 30 cm. The 

 growing region remains basal to the leaf and the rate of growth during 

 the course of development is much flatter than in stems, presenting 

 some of the features of root-tips. 



Three objects were in view in the measurements of the rates of 

 elongation: (1) estimation of the rate in alterations from a low to a 

 high temperature and vice versa; (2) accelerations due to changes from 

 one temperature to another; (3) the effects of small and of wide vari- 

 ations in temperature. 



The principal data concerning the experiment are given in table 101. 



Table 101. 



The maximum rate displayed was at a temperature slightly under 

 30° C, varying, of course, with the preceding experience. Rising 

 temperatures are seen to accelerate growth with a coefficient sHghtly 



