AS A FUNCTION OF LIVING PROTOPLASM. 297 
No. II. 
| R. Y. G. V. cl. D. 
| 070 065 083 070 079 Mean of 
076 026 089 | -087 | 090 fourteen 
084 066 ‘072 070 *O€7 | observations: 
Means «| 077 052 | 081 | -076 | -079 073 
Taking the means again of the above, the results are as 
follows :— 
R. Y. G. V. Cl. D. 
058 043 058 =. ‘059 060 ‘053 ; 
or, practically, 
‘06 04 "06 ‘06 :06 05. 
It will be seen that these means agree very closely with 
what is experienced with green plants; in so far as red, 
violet, and clear light furnish maxima, yellow, and generally 
green as well as total darkness, minima. These results, more- 
over, agree with those obtained by Wiesner, who found that 
etiolated plants absorbed the same rays, but in a lessened degree. 
Temperature, however, bears so important a part that appa- 
rently exceptional results may easily mark the general law. 
A somewhat conspicuous difference will be observed between 
the effects of green light on the two specimens: thus, while 
No. I. has the most decided minimum, No. II. has the most 
decided maximum. I met with a similar experience when 
experimenting with green plants; thus, while one batch of 
Lettuces gave a mean under green the next lowest to that 
under yellow light, both a second and a third batch gave the 
mean under green next highest after red, violet, and clear glass. 
On the other hand, Palms gave the mean under green as the 
lowest minimum. 
The green glass used transmitted the absorption-bands 111. to 
vr. Hence there seems to be some peculiarity about the effect 
of green glass which requires further investigation. 
The lowest minimum is most constantly under yellow glass ; 
and the results with colourless glass agree therefore with those 
obtained with green plants, in which I have pointed out that 
yellow light must have a retarding effect on transpiration, since 
the glass used transmits all the red as well, whereas the red 
glass is absolutely pure without a trace of any other colour. It 
LINN. JOURN.—BOTANY, VOL. XXIV. 25 
