312 BOTANICAL GAZETTE [october 



Soil fertility. — From a study of the distribution of phosphorus, nitrogen, 

 calcium, potassium, and other elements in soils whose previous history and 

 crop yields are known, certain Rothamsted plots, Pennsylvania State College 

 fertility plots, and Strongsville, Ohio, plots. Van Alstine* draws conclusions 

 as to the movement of nutrient elements in the soil. 



Phosphorus used as a fertilizer moves but slightly in the Soil, remaining 

 fixed until removed by plants, or by the erosive action of water or wind. 

 Certain alkali salts stimulate a larger use of phosphorus, especially by legumes. 

 Potassium also is readily held by the soil, but moves somewhat more freely 

 than phosphorus when other fertilizer salts are used. It may then be carried 

 down beyond the reach of the root system. Nitrogen leaches out into the 

 drainage water to a certain extent, but the loss is small if the crop remains on 

 the soil throughout the growing season. Nitrogen will even accumulate in 

 the soil, mostly in roots and other residues. Carbonates wash out of the soil 

 readily, particularly in the presence of ammonium salts. Magnesium also 

 will leach under this circumstance. The calcium content of the soil decreases 

 as the carbonates go out, and with alkali fertilizers it decreases more rapidly 

 than acidity develops. In the presence of ammonium salts, calcium loss occurs 

 just about as rapidly as acidity develops. Such facts as these should be taken 

 into consideration in developing a rational fertilizer practice. — C. A. Shull. 



Suspensor of Trapa. — TisoN' has described a remarkable suspensor devel- 

 oped by Trapa natans. For some time during embryogeny the suspensor 

 region grows with remarkable vigor, the cells becoming numerous, as well as 

 very large and turgid. The embryo is finally differentiated at the tip of the 

 massive suspensor, which is also the source of nutritive supply to the embryo 

 during its earlier stages. Similar suspensor behavior has been described by 

 GuiGNARD among the Leguminosae, and by Treitb in certain Orchidaceae, but 

 in none of them does the situation seem to be so extreme as in Trapa. — J. M. C. 



Opuntia. — Griffiths" has pubhshed 8 new species of Opuntia, which he 

 has recognized in connection with cultures of Opuntia upon the Department of 

 Agriculture grounds at Chico, CaUfornia. — ^J. M. C. 



* Van Alstine, E., The movement of plant food within the soil. Soil Science 

 6:281-308. 1918. 



» TisoN, M. A., Sur le suspenseur du Trapa natans L. Rev. Gen. Botanique 

 31:219-228. pi. 4. figs. 5. 1919. 



"> Griffiths, David, New and old species of Opuntia. Bull. Torr. Bot. Club 

 46:195-206. pis. g, 10. 1919. 



