﻿70 BOTANICAL GAZETTE | January 



cotyledon. In Ranuncuhis Ficaria there is hardly a trace of a second cotyle- 

 don. In Corydalis cava the prominent cotyledon gradually assumes a termi- 

 nal position, causing a displacement of the stem tip so that it appears lateral. * 



Occasionally there is a slight protuberance which might or might not be the 

 rudiment of the other cotyledon. In Bunium also it was doubtful whether a 

 slight protuberance might be interpreted as the rudiment of the missing cotyle- 

 don. In Cyclamen persicuvi embryos in the ripe seed show no trace of a second 

 cotyledon. Attempts to induce the development of the missing cotyledon by 

 removing the prominent one gave only negative results. The paper would 

 doubtless have been more complete had it not been for the early death of 

 the writer. The experimental part certainly deserves another trial. Bunium, 

 which Schmid regarded as the form most favorable for experiment, was not 

 investigated, because material in the proper stages was not available. — C. J. 



Chamberlain. 



In A RECENT. SERIES of experiments upon the influence of diminished 

 atmospheric pressure upon the photosynthetic process, FriedeP^ has discov- 

 ered a curious condition of affairs. Young leaves oi Euonymus japonicus, 

 Rttsciis aculeattis, and Ligustrtim japoticion, and entire plants of Lepidiwn 

 sativum were used. A diminution in atmospheric pressure produces first a 

 decrease in the intensity of photosynthesis ; then this intensity passes through 

 a minimum, increases again to a maximum, and at last decreases to zero 

 when a pressure of about one-tenth of an atmosphere has been reached. 

 The minimum is from 0.4 to 0.6 of the normal intensity and is reached at a 

 pressure between 0.4 and 0.5 of the normal atmospheric pressure. The 

 maximum intensity (in Ruscus it is more than double the normal, in Ligus- 

 trum it is 0.7 of the normal) is reached at a pressure of 0.14 to 0.22 atmos- 

 phere. The author presents evidence that this is due to the joint action of 

 two causes : (i) a decrease in the partial pressure of CO2 brings about a fall 

 in the intensity of photosynthesis, while (2) a decrease in the total atmos- 

 pheric pressure occasions a rise. Changes in the partial pressure of oxygen 

 alone have no effect. Also, an increase in the volume of the air in the experi- 

 ment chamber causes a rise in photosynthetic activity. What may be the 

 exact meaning of these facts it is impossible to conjecture. Perhaps these 

 facts have some connection with the reputedly greater photosynthetic activ- 

 ity of alpine plants as compared with that of lowland forms, — Burton E. 



Livingston. 



McKenney37 has been conducting experiments upon the conditions of 

 light production in luminous bacteria. His own summary of the chief results 

 is as follows: (i) all acids are injurious to light production ; a slight excess 



3*Friedel, Jean, L'assimilation chlorophylUenne aux pressions inf^rieures a la 

 pression atmosph^rique. Rev. Gen Bot. 40: 337-355, 369-390. 1902. 



37McKenney, R. E, B., Observations on the conditions of light production in 

 luminous bacteria. Proc. Biol. Soc. Washington 15: 213-234. 1902, 



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