NOTES AND ABSTRACTS. 



609 



and wasteful system into a systematic and profitable method of treating 

 the woodlands is clearly set forth, the beautifully executed illustrations 

 going far to elucidate the text. 



The Sewanee forests cover an extent of about 5,500 acres, at 

 altitudes varying from 800 to nearly 2,000 feet. 



The Black Walnut, Juniper, Bitternut, Hornbeam, and Tulip Tree, 

 particularly the last, are the principal timber-producing species. 



A. D. W. 



Lysimachia crispidens. By W. B. Hemsley (Bot. Mag. tab. 

 7919). — Nat. ord. Primulacea, tribe Lysimachiece. Native of Central 

 China. Of the 120 species of this genus China has half of them. This 

 is a perennial herb, with numerous slender scapes with racemes of pink 

 flowers inch diam. — G. H. 



Lysimachia crispidens. By W. Irving (Gard. p. 389 ; 6/6/03). 

 — Although some doubt exists as to its complete hardiness, this plant has 

 already proved to be of great value in the cold greenhouse. It is quite 

 new to cultivation, having been comparatively recently collected in the 

 neighbourhood of Ichang, province of Hupeh, China. So far as we know 

 it has only bloomed with Messrs. Veitch and at Kew. It forms a rosette 

 of somewhat fleshy leaves not more than nine inches high, and bears a 

 profusion of pinkish flowers upon very slender pedicels. — E. T. C. 



Madeira and the Canary Islands, Botanical Journeys in. By 



J. Bornmuller (Engl. Bot. Jahrb. xxxiii. 1903, pp. 387-492; 8/12/1903).— 

 A systematic account of the flowering plants and Ferns collected by the 

 author during two journeys through the islands, with notes on the 

 distribution of the species and forms, and critical remarks. — A. B. B. 



Magnesium Salts : Under what circumstances are they 

 injurious ? By Oskar Loew (Flora, xcii. vol. 1903, pp. 489-494).— Despite 

 the part played by magnesium compounds in the metabolism of plants, in 

 the absence of calcium compounds they may act as poisons. Thus 

 Spirogyra dies rapidly in 0*1 per cent MgN0 3 but lives for weeks if in 

 addition 0*3 per cent. Ca 2N0 3 be supplied. The author's interpretation 

 is that Ca forms important combinations with proteids in nucleus and 

 chloroplasts. If Mg replace it the osmotic capacity is altered, and fatal 

 changes of structure are the result. If enough Ca compounds be present 

 to enter into the proteid combination, the Mg is excluded by the law of 

 mass-action, and the Mg is free to perform its normal part in metabolism. 

 Consequently for optimum results a definite Mg : Ca ratio must be 

 available for absorption. — M. H. 



Mango in Porto Rico. By G. N. Collins (U.S.A. Dep. Agr. Bur. 

 PL Ind. Bull. 28 ; 15 plates). — An exhaustive account of the intro- 

 duction, culture, uses, present status, packing, &c, of the Mango. Nine 

 Porto Rican forms are described and figured, and the desirability of intro- 

 ducing seven others, and the best method of so doing discussed. 



E. A. B. 



