230 



The Philippine Journal of Science 



1916 



greater in the light. But, as also previously suggested, I suspect 

 that this was due to the atmospheric moisture. The average 

 growth of reasonably active plants was usually greater in light 

 than in darkness. Such an average is meaningless, unless the 

 plants compared are at the same stage of the grand period of 

 growth of the shoot being tested; but, if such averages are 

 greater on the one side consistently, day after day, outside con- 

 ditions may be regarded as responsible. However, there were 

 constantly conspicuous exceptions to this rule, there being at all 

 times from one-third to one-half of the varieties of which the 

 most rapidly growing single plant was in the dark. 



Table II. — Growth of tubers of Dioscorea during one day, May 9-10. 



Col- 

 lege 

 No. 



Illumination. 



Growth in millimeters. 



Without soil. Tuber No. — 



In soil. Tuber 

 No — 



1 



2 



3 



4 



5 



6 



7 



S 



9 



10 



1 



2 



7 



3 



4 



952 



1369 

 958 

 960 

 331 

 951 



IDark 











6 

 6 











6 

 3 



19 



ILight 



11 

 12 





1 



4 









2 



(Dark __ 



2 



7 







5 





1 Light 















IDark 



14 







8 

 1 

 3 

 1 



16 

 70 



6 



4 



5 



157 









10 











(Light 







2 

 7 

 31 

 70 

 5 















[Dark 



3 



5 

 12 



1 

 33 



10 

 9 









40 



7 



16 

 62 



26 



1 Light 



17 



4 



4 



IDark 



9 

 5 

 2 







1 Light 



5 



4 



135 



4 



2 

 3 

 2 

 91 

 2 

 1 



4 

 2 



34 







IDark 



|Light-._ 



12 





6 

 4 





26 

 10 

 159 



1 



28 

 97 



25 



127 



4 



6 

 2 



26 

 2 



88 



IDark 



13 

 116 



3 



18 



26 

 4 

 2 



6 



24 

 4 



39 

 91 



76 

 121 

 61 



(Light 



956 



[Dark 



lLight._ 



4 

 9 



1 

 11 







1101 



IDark .. 



11 



120 

 7 

 5 

 7 

 12 



2 



31 



41 



5 







14 



32 

 5 



64 



5 

 7 



71 

 5 

 19 

 16 



ILight 



3 

 1 

 6 



31 

 2 



3 



329 

 1094 

 938 



IDark 















ILight 



5 



13 



3 





18 



5 

 7 



IDark... 





1 



iLight 



2 







2 







3 









IDark 







10 







7 

 1 



■ 



iLight 



3 











1 





























