NOTES AND ABSTEACTS. 



481 



one botanical species which has been profoundly modified by cultivation. 

 This bulletin describes the different groups of soy-bean at present in 

 cultivation and gives a list of several hundred varieties of which the 

 seed has been imported into North America, with a description of the 

 characters of each as developed at different experimental stations in the 

 Dffited States.— M. L. H. 



SpathOgflottiS plicata. By F. Ledien {Orchis, vol. v. pt. iii., 

 p. 40; 1 plate). — This well known orchid is depicted in a coloured 

 plate.— E. W, 



Spinach Troubles at Norfolk, Virgrinia. L. L. Harter {U.S.A. 



Exp. Stn. Virginia, Bull. 4, Aug. 31, 1910; plates). — The spinach 

 crop in the market-gardening districts of Norfolk, Va. , has been getting 

 shorter for some years, and this bulletin sets forth the results of investi- 

 gations as to the causes of this gradual failure. The seasons have been 

 very dry, but it is said not to have been drought only from which the 

 crop has suffered. There were three diseases affecting the spinach in 

 Tidewater, Virginia, leaf-spot, mildew, and malnutrition. It is with 

 the last only that this bulletin is concerned, and the writer attributes 

 it to the excessive use of chemical manures in the region, and the conse- 

 quent disappearance of humus and accumulation of acid in the soil. 

 Norfolk soils are naturally deficient in organic matter, and the practice 

 of applying nothing but chemical fertilizers is therefore specially inad- 

 visable in that region. The reasons why humus in the soil is bene- 

 ficial are pointed out, and its possible sources of supply, horse-manure 

 and green manure, are mentioned, and the best method of their applica- 

 tion described. Crop rotation is also said to be indispensable, although 

 the choice of crops in such a rotation depends to a great extent on the 

 economic and natural peculiarities of each district, and it is unfortunate 

 that there is no deep -rooting green crop suitable to the conditions in 

 the locality. 



The functions of micro-organisms in the soil and the relation of 

 lime to micro-organisms and humus in the soil are also discussed. 



i¥. L. H. 



Spring- Frosts, Damage to Plants. By F. Eochau {Garten- 

 flora, vol. Ix. pt. V, pp. 116-120). — Late frosts damage land plants 

 by driving the water out of the cells into the intercellular spaces, where 

 it freezes. The cell contents are concentrated and a change in. the 

 constitution of protoplasm takes place. If the plant is very slowly 

 thawed the cells again take up water, and the protoplasm may con- 

 inue to live in favourable cases, but if there is a sudden rise of tem- 

 3erature the roots resume their activity, the altered cells are unable 

 o circulate the water supplied to them, and the plant dies.— /S^. E. W . 



Sterility in Fruit Trees. By E. Wallis {Jour. Agr. Vict. 

 Ian. 1911, pp. 10-19). — In Victoria, such kinds as * Keiffer's Hybrid ' 

 ind ' Winter Nelis ' pears, ' Northern Spy ' apple, \ Coe's Golden 



VOTi. XXXVII. I I 



