234 BOTANICAL GAZETTE [SEPTEMBER 
and Triticum vulgare, with the view of testing the applicability of the ideas 
set forth in BLAcKMAN’s® “optima and limiting factors” to the process of respira- 
tion. In general the experiments were run six hours, and the CO, production 
determined for each hour. Up to 10° the CO, produced per hour was constant 
for the six hours. At higher temperatures, up to 20°, there was a rise for four 
or five hours. This rise is hard to explain in the light of the facts that the seeds 
were germinated at approximately 20°, that it occurred regardless of the age 
of the seedlings, and that it was followed by a corresponding fall. At constant 
temperatures above this, up to 40°, a fluctuation in CO, production was apparent. 
Especially between 30° and 40° this manifested itself by a rapid fall for the first 
two hours, followed by a later rise ranging over one to two hours, followed by a 
later continuous fall. ‘The author assumes that two distinct processes are differ- 
ently affected by the continuous high temperature: one early depressed, marking 
the fall; the other latér stimulated, showing the rise. This fact he suggests may be 
related to the double nature of CO, production in respiration noted by PALLADIN, 
in which he assumes the action of oxidase on the one hand and of carbonase on 
the other. At still higher temperatures there is a continual fall in CO. production. 
The temperature at which one type of behavior changes to another is determined 
by the nature of the stored food, as the following tables show: 
Lupinus Pisum Triticum 
Rise noticeable 15-20° 20-25° ai 
Fluctuation o-25° 30° 35° 
Continual falling ano aS" ae 
Protein 37% 22% 12% 
Starch none 54% 74% 
The Van’r Horr law applies for Pisum and Triticum from 0°-20°, and for 
Lupinus up to 25°. The coefficient for a temperature difference of 10° lies between 
2 and 3. The continual falling in CO, production with continual exposures : 
higher temperatures agrees with BLACKMAN’s results. BLACKMAN found that ® 
photosynthesis the initial rate at any given high temperature (30 40°) could be 
figured in two ways, giving agreeing results: by applying the VAN’T HoFF coef 
cient to the measurements at lower temperatures where the rate is Cons'®" » 
by taking several later determinations at the given temperatures and from 
extrapolating the initial value. KutypEr finds that these methods will not apply 
to the CO, yield in respiration, because of the appearance of the two antagonist 
factors at temperatures between 30° and 4o°, and because of the non-application 
of the Van’r Horr law at the higher temperatures.—WILLIAM CROCKER. 
Permeability.—Czaprk® has published a preliminary article upo? the mat 
of various reagents upon the precipitation of tannins in plant cells by Tote 
of caffein and ammonium carbonate. If slices from the epidermis of Echever 
8 BLACKMaN, F. F., Annals of Botany 19:281-295. 1905- 
9 CzAPEK, F., Versuchs iiber Exosmose aus Pflanzenzellen. 
Gesell. 28:159-169. 1910. 
Ber. Deutsch. Bot. 
ig a ie all ae 
