USE OF THE SPECTROSCOPE IN STUDY OF PLANT LIFE. 91 



Lettuces (second series). 

 Eange of Temperature 57^-66°. 



No. 



R. 



Y. 



G. 



B. 



V. 



01. 



I. . 



1-13 



1-05 



1^04 



1^15 



1^42 



1-54 



II. . 



•81 



•54 



1-02 



•33 



1-08 



•68 



III. . 



1-22 



1-20 



1-12 



1^50 



1^55 



1^35 



IV. . 



1-89 



1-10 



1^87 



1^54 



1^59 



1-39 





•92 



1-35 



•97 



•73 



1^20 



1^33 



vl : : 



1^93 



1^40 



1-29 



1^50 



2^41 



1^58 



Total 



7-90 



6-64 



7-31 



6^75 



9-25 



7-87 



As in the preceding series, one maximum occurs under the red, 

 another under the violet or most refrangible end, while yellow is again 

 a minimum. Green gives a rather higher result than before. Com- 

 bining the two series, the mean of the two totals is as follows: — 



R. Y. G. B. V. CI. 



7-29 6-39 6-98 6-70 949 7-37 



This result clearly shows the preponderating effects of the red and 

 violet ends of the spectrum ; and they are, of course, just where the 

 strongest chlorophyllian absorption-bands occur. 



Clear glass gives a decided maximum, though in many cases the 

 loss is less than under violet alone ; hence I would repeat, and I believe 

 the observation has not been made before, that yellow light has a 

 decidedly retarding influence upon the amount of water exhaled by 

 red and violet lights. 



Though such is the case with the rapidly transpiring herbaceous 

 leaves of the lettuce, it appears to be somewhat different with palms 

 and box, as the following series will show; for out of ten observations 

 on palms, on seven occasions the loss under clear glass was greater 

 than under violet, and on six occasions greater than under red. With 

 lettuces the loss under clear glass was on as many occasions greater 

 than that under the red glass as the reverse. In the case of the box, 

 however, the loss under red and violet was always greater than under 

 clear glass. But the preponderance of red over yellow is not so pro- 

 nounced as with lettuces. 



Lettuces (third series). 

 Eange of Temperature 53^-58^. 



No. 



R. 



Y. 



G. 



B. 



V. 



Cl. 



I. . 



•70 



•68 



•43 



•44 



1^07 



•46 



II. . 



•30 



•27 



•81 



•49 



•55 



•62 



III. . 



•80 



•55 



•77 



•59 



•89 



•62 



IV. . 



•58 



1^10* 



1-45* 



•72 



" 1-83 



•70 



V. . 



•29 



•43 



•72 



•30 



•81 



•59 



VI. . 



1^44 



141 



1^24 



1^76 



•97 



2 13 



Total 



4^11 



3-28 



3-97 



4-30 



612 



512 



Mean 



•68 



•65 



•79 



•71 



1-02 



•85 



