592 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Too much heat scalds the heads, which then rot off. In three weeks 

 to a month pull up the plants, turning the manure over to the row 

 next in succession for forcing. Cut off the heads for market : they will 

 keep fresh for two or three days. The roots can be used to feed cattle or 

 pigs, but are apt to taint the milk of dairy cows. Or they may be laid by 

 the heels in a cellar, or planted out again, when they throw up fresh 

 leaves, which form an excellent salad. The main points for the gardener 

 are to select the best seed ; not to sow before July, so as to check root 

 development ; and to force by moderate top heat, never from the bottom. 



F. A. W. 



Chlorophyll in the Young- Shoots of Woody Plants, On the 

 Distribution of. By Daisy G. Scott (Ann. Bot. vol. xxi. July 1907, 

 pp. 437-439). — A brief note on the distribution of chlorophyll in young 

 shoots of Jasminum nudiflorum. In the stem of this plant chlorophyll is 

 found in the palisade layer, many cortical cells, pericyclic parenchyma, the 

 medullary rays, and some of the medullary cells bordering on the pro- 

 toxylem. A table is also given showing the distribution of chlorophyll in 

 the shoots of some thirty of our common trees and shrubs. — A. D. C. 



Chloroplast considered in Relation to its Function, The 

 Structure Of the. By J. H. Priestly and Annie A. Irving (Ann. Bot. 

 vol. xxi. July 1907, pp. 407-413). — Plants of Selaginella Martensii, 

 S. Kraussiana, and Chlorophytum elatum were selected for investigation 

 on account of the large size of the chloroplasts. The chloroplasts of 

 Chlorophytum consisted of a network with chlorophyll in the meshes. 

 In optical section a distinct peripheral layer was observable which con- 

 tained the colouring matter. These points were discernible in either 

 living or fixed material. In the case of Selaginella living material 

 was unsatisfactory, but when frozen in gum and glycerin, or when 

 properly fixed, showed a microscopic structure in agreement with that 

 of Chlorophytum. 



The authors agree with Timiriazeff, who showed that the energy- 

 transformation taking place in the chloroplast required that the 

 chlorophyll should be distributed in a very thin layer, and that the 

 thinner the layer in which a definite amount of chlorophyll is disposed 

 the greater the amount of energy set free. — A. D. C. 



Chrysanthemums : French Introductions, 1906-7. By 



G. Clement (Rev. Hort. January 1, 1907, pp. 18-21 ; and January 16, 

 1907, pp. 49-51 ; 1 woodcut).— A descriptive list of a large number of 

 varieties with their raisers. — C. T. D. 



Cicada, The Periodical. By C. L. Marlatt, M.S. (U.S.A. Dep. 

 Agr., Bur. of Entom., Bull. 71 ; July 1907 ; 6 plates and 68 figs.).— 

 A monograph of over 180 pages dealing exhaustively with the periodical 

 cicada, and giving a summary of the habits and characteristics of the 

 insect, the races, broods and varieties, and the distribution of the various 

 broods. Then follow detailed accounts of structure, habits in all stages, 

 and the natural enemies of the cicada, the best preventive and remedial 

 measures, and a complete bibliography of the insect.— F. J. C. 



