390 BOTANICAL GAZETTE [May 
aquatic plants collected. HHANKINSON then considers the lake fauna in general, 
concluding with a summary of the life and the life conditions of the littoral and 
abyssal parts of the lake. Following an appendix with diversified matter are a 
large number of excellent plates, most of which illustrate the characteristic lake 
habitats —HEnry C. Cowles. 
Various colored lights and photosynthesis.—It is fast becoming evident that 
the telling work in the advance of plant physiology is to be done by men who are 
prepared to work by the exact methods of the physicist and chemist. One feels 
that Knrep and MinpER*4 have indicated the way for the final settlement of the 
perplexing question of the part played in photosynthesis by the various portions 
of the spectrum. They have given great attention to developing suitable 
screens and to accurate methods of determining the energy values of the light thus 
obtained. This is apparently done with exact knowledge and application of 
the physics involved. Although it is unfortunate that the rate of synthesis must _ 
be tested by the bubble method, this seems to be the least objectionable method 
available. In the light used all heat, as well as infra-red and ultra-violet rays, 
was cut out by distilled water containing traces of potassium bichromate and 
ammoniacal copper sulfate. The screens were specially made colored glass, the 
spectra of which were fully studied. The measurements were made between 
II A.M,and 12:30 P.M. by means of reflected sunlight. The present paper reports 
the results of measurements of the synthetic value of equal energy intensities (as 
shown by the blackened thermopyle) of red light (620 4 toward the infra-red), 
blue light (523.8 toward the ultra-violet—little transmission to the left of 
509 Mu), and green light (512-524 uu). Green gave no photosynthesis. Red 
and blue of equal energy value gave equal photosynthesis. This finding is quite 
in contrast with the current conception of plant physiologists who hold that the 
blue end of the spectrum plays little part in the process. This view is due to the 
fact that the blue screens commonly used reduce to a much greater degree the 
energy intensity than do the red. It is evident that the relative value of the — 
portions of the solar spectrum is approximately proportional to the relative 
energy amounts of the two portions. These relative amounts vary with the time 
of day, cloudiness, humidity, altitude, etc., the red, of course, being in general 
greater, but the blue far from negligible. The writers mention that this is only 
the first step in this important work. They hope by the use of suitable screens, 
or prism-resolving methods, to study the photosynthetic value of each portion 
of the spectrum on the basis of its energy value, and to construct a complete 
curve of this value-—Wwm. Crocker. 
e seeds 
Germination of the seeds of certain parasites.—The germination of th 
ively 
of various parasites belonging to the Rhinanthaceae has been rather extens 
investigated. Two of the more recent studies illustrate two of the more prominen 
24 KEP, H., UND MINDER, F., Ueber den Einfluss verschiedenfarbigen Lichtes 
auf die Kohlensaureassimilation. Zeit. Bot. 1:619—650. 1909- 
