Periodical Literahtre 145 



Respiration is a measure of physiological 



Respiration processes in leaves in general, and in so 



of far of practical interest. G. Schmidt in 



Perennial Beitrixge zur Wissenschaftlichen Botajiik 



Foliage. (1903), publishes a comprehensive study on 



the changes in intensity of respiration of 



evergreen plants during the several periods of vegetation during 



which their leaves persist. The same weight of leaves of 



Rhododendron maximum emitted during the first summer 2.66 



volume per cent COj, in the following winter only 1.36, in the 



second summer 1.38, the second winter 1.16, the third summer 



.95. Similar results are recorded for Buxjis and Hedera, the 



old leaves respiring about half as much as the younger. 



For experiments with spruce twigs from botanical garden in 

 the neighborhood of Leipzig covered with soot to over 13 per 

 cent of their own weight (which the rains, however, wash off) 

 and others from a distant forest. The leaves of two years dura- 

 tion of both specimens respired in summer equal amounts of COj 

 (1.45 %), but those of the first year in the garden specimen re- 

 spired more (2.07%) than the forest specimen (1.83%). In 

 winter the older leaves again worked approximately with equal 

 intensity, but the young leaves of the garden considerably less 

 (1.41 : 1.76). Generally speaking, however, similar gradual 

 reduction with the age of the foliage takes place, as recorded 

 for Rhododendron , the performance in the second winter being 

 reduced by 35 to 50 per cent of that in the young leaves. Twigs 

 respire in the same sense. The respiration curve sinks in winter, 

 rises, but not to the level of the first summer, in the second sum- 

 mer, falls deeper in the second winter and continues sinking in 

 the following seasons. 



Ueber die Attnung ein- und mehrjdhriger Blatter irn Sommer uvd im 

 Winter. Centralblatt fiir das gesammte Forstwesen, March, 1906, p, 139. 



Some of the results of a very comprehen- 

 Chemistry sive work on investigations of the wood 



of substance by V. Grafe, are summarized as 



Wood. follows : 



I. The reactions of wood substance, dis- 

 covered by Wiesner, namely yellow color with aniline salts, red 

 color with phloro-glucin-hydrochloric acid and coloring with other 



