NOTES AND ABSTRACTS. 



833 



Manettia, The Cultivated Species of. By T. A. S. (Gard. 

 Chron. No. 936, p. 384, fig. 169; Dec. 3, 1904).— Though there are 

 between thirty and forty species included in this genus, there appear to be 

 only five cultivated in Europe. Of each of these species the writer of the 

 paper gives a short account, alluding particularly to their habitats and 

 synonyms. — G. S. S. 



Manganese in Plants. By Josef Gorsl (Prague) (Beili. Bot. Cent. 

 xviii. Abt. i. pp. 119-132). — Has investigated the occurrence of man- 

 ganese, and finds that it is exceedingly common, especially in water 

 and marsh plants, which contain more than those of dry ground. It 

 can be distinguished from the other isomorphous double ammonium 

 salts by treatment with ^ KMn0. t . Conifer a contain much man- 

 ganese. By researches with fungi the author shows that it has a 

 stimulating effect on growth and fructification, but not under all cir- 

 cumstances, for the concentration and character of the nutritive solution 

 affect this.— G. F. S.-E. 



Mangold and Beet : Investigations on the Physiological Basis 

 of Cultivation. By C. Kraus (Nat. Zeit. Land-Forst. i. pp. 180-200, 

 220-237, 268-279, and 342-367, 1903 ; and ii. pp. 65-80, 1904).— The 

 differences in the varieties of Beta (Beet and Mangold) are treated from 

 a standpoint much more scientific than is general in agricultural researches ; 

 at first sight one may fail to see the practical bearing, but the research 

 is really directed towards ascertaining essentials which underlie all practice. 

 Starting with germination, it is shown that the differences in form, 

 structure, and utility of varieties of Beta are traceable to the part taken 

 by the taproot, hypocotyl, and epicctyl respectively in the formation of 

 the swollen tuber, and the extent to which these contribute to growth in 

 length and thickness. The internal structure — including number and 

 breadth of the growth-zones — is also correlated with the mode of growth 

 and external shape. The structure and growth also determine the 

 maximum size attainable by any variety, and the manner in which it will 

 respond to external conditions, either natural or artificial. Crop-production 

 and nutritive value are also bound up with structural differences. The 

 paper is an important one in regard to raising new varieties, which are too 

 often the outcome of chance. The numerous experiments carried out 

 include tests of the effects of earthing up the crowns, as against leaving 

 them exposed. There is a good deal to be said both for and against the 

 two systems, but a moderate earthing up improves the yield of most of 

 the varieties. — W. G. S. 



Mangroves, Excretion of Salt by. By Johs. Schmidt (Flora, 

 xciii. 1904, pp. 260-1).— In JEqiceras alone is the excretion of NaCl by 

 glands on the upper surface of the leaves. If this occurs in other Man- 

 groves, which has yet to be proved, its method must be different. — M. II. 



Manure, Town Stable. By B. Dyer (Jour. Agr. Sc. vol. i. part i., 

 pp. 108-113, Jan. 1905). — Town manure is so largely used in gardens, 

 especially for vegetable culture, that this article is a particularly useful one 



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