240 



The Philippine Journal of Science 



practically the same. At this temperature, there was no con- 

 siderable checking of the rate of growth. When I succeeded 

 in keeping the temperature constantly at 8°, growth seemed to 

 be influenced slightly, but when it rose to 16°, growth was not 

 appreciably different from that of the control stems at a tem- 

 perature throughout of, say, 26°. Better arrangement of the 

 experiment would of course effect temperature down nearly to 

 the freezing point. To do this temporarily, I disjointed the 

 outer tubes and fill them with shaved ice, and kept this up, 

 renewing the ice constantly, for a period of two hours. The 

 effect of this was to check the growth quite appreciably, and 

 this effect continued, and finds expression in the growth during 

 the twelve hours from 7.30 at night, May 28, to 7.30 the follow- 

 ing morning. During the ensuing twenty-four hours, the plants 

 which had been subject to local chilling grew faster than the 

 control plants, which may be construed as merely showing that 

 the effect of the treatment had been completely overcome. De- 

 tails of this experiment are shown in Table IX. 



Table IX. — Effect of cold on stems of Dioscorea hirsuta. 



[Measurements of growth are recorded in centimeters.] 



Date. 



Tuber No — 



Remarks. 





1 



6a 



66 



9 



May 25-26.. 



18.0 



14.1 



12.5 



14.1 

 14.9 

 6.9 





May 26-27.. 



20.6 



13.2 



14.6 





May 27. 6 p. m., to May 28. 



6.7 



4.9 



6.6 



Cold water turned through 66 



9 a. m. 











and 9; temperature at 9. 20 a. m.. 



May 28: 











6°C. 



la. m 



» 161. 



■164.3 



-128.2 

 1.5 



•134.0 

 1.3 





11.30 a. m 



1.7 



0.6 



Room temperature at 10. 30 a. m.. 















26° C. Water slowed at 12 m.. 













temperature then, 8°. 



1.80 p. m 



0.9 



0.7 



1.4 



1.0 



Temperature at 1 p. m: Room, 















28°; 6 6, 16°: 9. 19°. 



3. 30 p. m 



1.3 



0.8 



0.7 



0.9 



Temperature at 3 p. m.: Room, 















27°; 6 6 and 9, 8°. At 3. 15 flow 













was checked in 9, temperature, 













16°; corrected, dropped to 8°. 



6.30 p. m 



1.3 



0.7 



0.8 



1.0 



Temperature at 4. 20: Room, 28°; 















6 6 and 9 (outflow), 8°. 



7.80 p. m 



0.9 



0.3 



0.3 



0.6 



Shaved ice put in place of cold 















water, 5. 30 to 7. 30; temperature 













then about 3°. Room temper- 



May 29. 7.80 a. m 



May 30, 7.30 a. m 



May 31. 6 p. m 



4.6 



8.9 

 8.6 

 31.6 



2.3 



8.1 

 7.7 

 21.9 



1.1 

 10.6 

 15.3 

 65.3 



2.1 

 11.5 



8.1 

 46.8 



ature at 7. 30 was 27. 5°. 



June 6, 10 a.m... 





. . 













* Total length at 9 a. m., May 28. 



