126 



VII. 



How crops are composed, how they feed. Chemistry of plant- 

 products and of plant-life. 



JAY DUNCAN. The fruit of Cornus (?) stolonifera (i). (them. 

 News, 1910, 101, pp. 217-218; Journ. Chem. Soc., London, 

 June 1910, abs. ii, 534). 



The dry berries contain 3 / of ash, n.5/ f a substance re- 

 sembling dextrin, about 38 % f sugars, and 3.5 % f nxe< ^ ^- 

 The sugars present include dextrose and maltose. Tartaric, oxalic 

 or citric acid could not be detected. 



D. THODAY. Experimental Researches on Vegetable Assimi- 

 lation and Respiration. ( Some Experiments on Assimil- 

 ation in the open air. Royal Soc. June 16, 1910. Reviewed 

 in Nature, Vol. 83. London, June 23, 1910, p. 511). 



In these experiments Sachs' half-leaf dry-weight method has 

 been employed, with modifications suggested in a previous paper 

 for avoiding errors due to shrinkage of the insolated half-leaves. 

 Turgid leaves of Helianthus annuus were found in bright sunlight 

 to increase in dry weight 17 mg. per hour per sq. decim. ; thus 

 Sachs' high value is confirmed. Even a slight loss of turgor, how- 

 ever, was accompanied by a diminution in the rate of increase. 



For this high rate of assimilation a leaf-temperature of 23C to 

 24C is probably required. It is suggested that Brown and Escom- 

 be's low results in bright diffuse light indicate that the stomata of 

 Helianthus leaves open to their full extent only in light which is 

 similar in quality to sunlight and approaches it in intensity. 



Detached leaves of Catalpa bignonioides when fully turgid increased 



(i) In the text of the Abstracts of the Journ. of the Chem. Soc. the name 

 given is Cornacea stolonifera, corresponding probably to the Cornus stolonifera 

 of the Index Kewensis (Ed). 



