636 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



and the flowers become blue again on reaching the normal temperature 

 (about 20° C). The same colour-changes occur in the case of flowers 

 killed by chloroform or steam, and in watery extracts of the anthocyan 

 pigment of the flower; hence they are quite independent of the living 

 cells containing the pigment. Similar changes were also observed 

 in flowers of Geranium, Iris bohemica, Viola hortensis, Salvia, Azalea, 

 &c. , but in these cases a greater rise in temperature (usually of about 

 30°) is necessary before the change begins — in the Erodium species a 

 rise of only 3° or 4° is suflicient to cause a distinct change of tint. 

 The author suggests that dissociation phenomena play a part in this 

 remarkable phenomenon of pigment alteration by heat. — F. C. 



Conifers, Disease of. By J. E. Weir {Phytopathology, ii. p. 215; 

 Oct. 1912). — Eeports a disease of conifers which causes the killing 

 back of the young shoots. It is due to a fungus probably identical 

 with Botrytis Doiiglasii and attacks many other conifers besides the 

 Douglas fir. It is common in the North-western States in the forests. 



F. J. C. 



"Copyright" in Horticultural Varieties. By Casimir 



Peyron {Rev. Hort. d'Alg. p. 90; March 1912).— The question of 

 securing due recognition and remuneration to the raisers of valuable 

 novelties has been mooted at various horticultural meetings, but is not 

 an easy one to solve. This article suggests the need of legislation 

 on the subject and states the difficulties in the way. — M. L. H. 



Cotton Plant, Some Principles of Hybridization as Applied 



to. By Dr. Trabut {Rev. Hort. d'Alg. p. 130; May 1912).— Any 

 plant which has been under cultivation from early times is liable 

 to be so much modified and altered in different ways that it is almost 

 impossible to arrive at what was its primitive wild type. If the 

 cultivated race as we have it is the result of crossing several primitive 

 species, the problem becomes even more complicated. This is the 

 case with the cotton plant, which has been cultivated in the Old World 

 from a remote period and has, moreover, in later times been crossed 

 with American strains. From this complex origin the cotton plant 

 has acquired an extraordinary faculty of adaptation — it is in perpetual 

 mutation. By a course of uncertain efforts or of fortuitous coinci- 

 dences, races have been formed in the principal centres of cultivation 

 differing widely from each other, and when industrial exigencies have 

 suggested extending the culture of cotton to new districts the problem 

 of choice among these races is much more difficult to solve than 

 is generally supposed. For the second time since the French occu- 

 pation of Algeria this question has come prominently forward. In 

 1853 one Hardy, who was then at the head of this department in 

 Algeria, popularized a variety called Georgie longue sire, which seems 

 to have been of a high economic value, but the origin of which is 

 no longer discoverable. This variety was unfortunately lost to culti- 

 vation through two causes. The American War of Secession so much 



