120 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Germination of Seeds (Le Jardin, vol. xxii. No. 518, p. 204 ; 

 July 5, 1908). — M. Demoussy {Bull, des Comptcs-rcndus Ac. Sc.) has 

 calculated the influence of the hygrometric state of the atmosphere 

 on the vitality of seeds. He finds that when it exceeds 0*7 at a tempe- 

 rature of 25° C. many seeds perish : the Cruciferae are among the most 

 resistant. A drier atmosphere is more generally favourable, but chervil, 

 poppy, and Digitalis suffer in dry air. Parsnips can stand a hygrometric 

 depression to OS.—F. A. W. 



Gnetum Gnemon, Embryo of {Bot. Gaz. July 1908, pp. 43-50. 

 with 1 plate). — Professor John M. Coulter describes the embryo sac, 

 embryo, and endosperm-development. — G. F. S.-E. 



Grafting-, Modifications in the Constitution of Plants produced 



by. By M. C. Laurent (Jour. Soc. Nat. Hort. Fr., p. 713, December 

 1908). — These modifications are of three sorts — in external appearance, 

 in chemical constitution, and in resistance to parasites — and the result of 

 M. Laurent's investigations goes to prove that the actual chemical com- 

 position of grafted plants differs from that of either stock or scion on its 

 own roots. — M. L. H. 



Growth, Laws Of. By Georg Ritter (Beih. Bot. Centralbl. xxiii. 

 l fc ~ Abth. Heft 3, pp. 273-319). — This is an important biometrical study of 

 the growth in length, in surface and in cubic contents of various plant 

 organs such as internodes, length and size of seeds, dimensions of leaves 

 in various habitats, &c. 



The author concludes that, in organic growth, the law of Quetelet is on 

 the whole confirmed. Up to a certain point the process of formation 

 seems to be independent of external conditions. A tendency to exceed or 

 fall short of the mean is regulated by inheritance and must be inherent in 

 the protoplasm. 



When material has been obtained from different localities in which 

 selection has been at work, the curves found show distinct differences. 

 New culminating points may appear, and there may be a change in the 

 value of the mean character. When a new maximum has been established 

 by selection, the development may be discontinuous but is still on the same 

 lines, and is only influenced by degrees. This holds of Giantism, Nanism, 

 Malformations, Anomalies, &c. 



The author remarks how the so-called Fibonacci series seems to under- 

 lie the laws of growth in almost all the cases studied. 



These extracts may serve to show the importance of this paper in 

 biometry, but it is exceedingly difficult to give any satisfactory abstract of 

 the author's conclusions without a far larger space than is here available. 



G. F. S.-E. 



Guatemala Plants, New. By John Donnell Smith (Bot. Gaz., 

 xlvi., August 1908, pp. 109 117). — New species of Capparis, Eurya, 

 Picramnia, Dalbcrgia, Miconia, Clidemia, Centropogon, Ardisia, 

 Stylogyne, Gonolobus, Solcnop)hora, Pilca, and Myriocarpa. — G. F. S.-E. 



Gum Disease of Citrus Trees in California. By Ralph E. Smith 

 and O. Butler (U.S.A. Exp. Stn. California, Bull. 200, 1908; with 



