Relation of Growth to Temperature. 49 



The sections swelled at temperatures of 15-23 0 C, were .20 

 mm., those at higher temperatures, .18 mm. in thickness. 



Plates of agar, 90 parts and oat-protein, 10 parts, show the 

 highest hydration capacity of any mixture tested, the measure- 

 ments obtained being as follows: 



Temp. 



15-16° C, .18 mm, 

 22-23° C., .18 mm 

 30-31° C, .16 mm 

 38-39° C, .18 mm 



46-47° C, .18 mm. 



48-49° C, .16 mm 



4 Hours. 



8 Hours. 



10-12 Hours. 



20-23 Hours. 



1.167% 



1.459% 





1.794% 



1.388 



1.550 





1,900 



2,172 



2.763 





3.078 



2.541-6 



2,86l 



(12 hours) 



Complete 







2,791% 





2.555-5 



2,833.1 



(10 hours) 



Complete 







2,361% 





1,906.3 



2,031 



Complete 





The swelling of discs 10-12 mm. in thickness, cut from joints 

 of Opuntia, in water and salt solutions in illustrated by the follow- 

 ing measurements: 



Percentage of increase and duration of swelling. 





Dist. Water. 



Potass. Nitrate, 

 .01 M. 



Potass. Nitrate Citric 

 Acid, .01 M. 



18- 



-20° 



C 



11.8% (42 hrs.) 



14% (42 hrs.) 



8.8% (32 hrs.) 



24- 



-25° 



c 



13-6% (40 hrs.) 



14.4% (42 hrs.) 



13.2% (42 hrs.) 



44- 



-45° 



C 



7.6% (5 hrs.) 



8.4% (7 hrs.) 



4.9% (2.5 hrs.) 



The swelling of the biocolloids is seen to increase in initial 

 velocity and total amount to a maximum between 39 0 and 46 0 C. 

 in the salted mixture, and to 46 0 C. in the unsalted plates. The 

 sections of plants increase similarly to a point undetermined and 

 the swelling may be much greater in preparations freed from 

 mechanical tissues. These increases are parallel to accelerations 

 and retardations of growth by living plants under the influ- 

 ence of temperature. 



The hydration in question constitutes 97 per cent, or more of 

 the volume increases known as growth and manifestly may not 

 be regarded as the form of imbibition to which Chatelier's theorem 

 may be applied simply as has been attempted by Taylor and 

 others. The relation to swelling demonstrated in the above 

 tables is one which finds a parallel in the action of agar-agar in 

 my experiments. The high swelling coefficients displayed by the 

 mixtures are probably associated with or due to the fact that the 



