- 127 - 



5 to 6 mg. per hour per sq. decim. in bright sunlight; in this plant 

 stomata occur only on the underside of the leaf. 



The effect of detachment from the plant upon the rate of 

 assimilation is considered, and evidence is adduced in support of 

 Sachs' assumption, ir^ the case of H. annuus, that concurrently 

 with assimilation, part of the products of photosynthesis are trans- 

 located from leaves still attached to the plant. 



S. B. SCHRYVER. The Photochemical Formation of Formalde- 

 hyde in Green Plants. (Proc. Roy. Soc., 1910, B. 82, 226- 

 232. --Jour. Chem. Soc., April 1910, Abs. 334). 



When grass was washed with warm water no formaldehyde 

 could usually be detected in the washings; if, however, the grass 

 was extracted with methylated spirit, the extracts on evaporation 

 and treatment with ether gave a solution which almost always con- 

 tained formaldehyde. It is argued that chlorophyll contains the 

 aldehyde in a state of stable combination. 



The photochemical formation of formaldehyde by chlorophyll 

 was confirmed; i c. cm. of an ethereal solution of chlorophyll was 

 allowed to evaporate at room temperature on a strip of glass 

 140X20 mm. 



Some films thus prepared were kept in the dark, others were 

 exposed to moist carbon dioxide in sunlight, others to sunlight over 

 lime or soda-lime, and others, again, were exposed to moist carbon 

 dioxide in the dark. No formaldehyde was formed in the dark, 

 very minute quantities were detected in the films kept in sunlight 

 over lime or soda-lime, whilst a distinct reaction was obtained from 

 films kept in sunlight over moist carbon dioxide. 



In attempting to explain the non-accumulation of formaldehyde 

 in the plant-cell, the author supposes that the reaction is similar 

 to one studied by Schiff. 



In presence of sunlight and carbon dioxide there is probably 

 a continuous synthesis of formaldehyde and a continuous conden- 

 sation of the latter to sugars, without that at any time such an ac- 

 cumulation of aldehyde be toxic to the cell. 



In testing for formaldehyde a modified and much more sensi- 

 tive form of Rimini's test was used. 



