120 SUMMARY OF CURRENT RESEARCHES RELATING TO 



general result, the exchange of gases is in autumn feebler in leaves than in 



buds, and, in the case of leaves, diminishes rajjidly before their fall. In 



the few weeks or days preceding the fall of leaves an energetic oxidation 



CO 

 takes place in their tissues. On the other hand, the proportion -~ remains 



below unity in certain cases, as the elm and lilac, during the winter period, 

 while in others it rises almost to unity in the spring. In some, as the 

 cherry, the proportion diminishes rapidly at the moment of unfolding of 

 the buds. The oxidation which takes place in buds in winter appears at 

 this period to decrease rapidly in intensity. 



7- General. 



Soraner's. Handbook of the Diseases of Plants.* — The first part of the 

 second greatly enlarged edition of this work treats of those diseases of 

 plants which are not due to parasites, and is divided into eight chapters, 

 as follows : — (1) Diseases caused by unfavourable conditions of nutrition ; 

 (2) by unfavourable atmospheric conditions ; (3) by injurious gases and 

 fluids ; (4) by wounds ; (5) formation of knots ; (6) galls ; (7) diseases due 

 to deliquescence ; (8) to weeds. 



Prehistoric Plants, t — In his address to the Biological Section of 

 the British. Association (Birmingham Meeting), Mr. W. Carruthers first 

 described the wonderful state of j^reservation of the flowers obtained by 

 Dr. Schweinfurth from mummy- wraiij)iugs in Egypt, even such evanescent 

 colours as the violet of the larksj)ur and knapweed, and the scarlet of the 

 poppy, the chlorophyll-remains in the leaves, and the sugar in the pulp of 

 the raisins, being preserved. The remains of 59 species of flowering plants 

 have been identified. 



In stratified clays resting on the boulder clay in the valley of the Nile, 

 have been found the remains of 2 species of Desmidiefe, 31 of DiatomaceaB, 

 and 9 of flowering plants, all belonging to the existing agrarian flora. In 

 another locality 51 species of moss have been determined with certainty, a 

 considerable proportion being alpine j^lants, one of them no longer found 

 in Britain. These beds also contain 7 species of seaweed now found in 

 our seas. 



The sedimentary deposits at Cromer, of later date than the Pliocene 

 strata, are the earliest in which remains of plants have been found that can 

 certainly be identified with species existing at the present time. Some of 

 the plant remains from Tertiary strata have been referred to still living 

 spscies, but, as Mr. Carruthers thinks, without sufiicient evidence. 



Strasburger's Practical Botany. | — This world-renowned book which 

 has already been translated into French and even Eussian, is now issued in 

 English, having been translated by Prof. W. Hillhouse. The author has 

 revised the translation and partly rewritten some portions. There are 

 many additional notes both by author and editor, those of the editor being 

 intended to either simplify or amplify the description or to enable the 

 n^aterial selected by the author to be replaced by some other, probably more 

 readily obtainable. The introduction on instruments and ai)i)aratus he has 

 nearly rewritten, to make it more suited for English students. 



* Sorauer, P.. ' Handb. d. Pflanzenkrankheiten,' 2te Aufl., ler Th., 920 pp., 19 pis., 

 and 61 figs. 



t Journ. of Bot.. sxiv. (1886) pp. 309-18. 



i See this Journal, 1885, p. 332. Engl, ed., 8vo, Loudon Swan. Sonueuschein, 

 Lowrv and Co., 1887. 



