AGBICULTTTEAL BOTANY. 823 



which indicate that mixing lime nitrogen with superphosphate does not decrease 

 the availability of the nitrogen but causes a decided reversion of soluble 

 phosphoric acid. The author, therefore, advises against the use of mixtures of 

 cyanamid and superphosphate. 



Available phosphates by furnace treatment, J. H. Payne {Amer. Fert., 

 41 (1914), No. 7, pp. 44-46). — Various processes proposed for obtaining available 

 phosphoric acid by heat treatment of phosphate rock are briefly described. 

 The prospect of successful commercial use of some of these processes is thought 

 to be good. 



Availability of phosphate to various crops {Wisconsin 8ta. Bui. 24O {1914), 

 pp. 22, 23, fig. 1). — In experiments which are here briefly noted, E. Truog 

 found in a comparison of ten different kinds of plants gro\vn under greenhouse 

 conditions with acid phosphate, rock phosphate, precipitated calcium phosphate, 

 aluminum phosphate, iron phosphate (both ferric and ferrous), magnesium phos- 

 phate, or manganese phosphate as sources of phosphorus that " contraiy to the 

 general belief that aluminum and iron phosphates are relatively unavailable to 

 plants, nine of the ten plants tested made better growth on aluminum phosphate 

 than on ealcuim phosphate, and six better growth on iron (ferric) phosphate." 

 This clearly indicates the inadequacy of chemical solvents as means of deter- 

 mining the availability of different phosphates. 



Notes on kelp and its potash contents, G. Surb {Mining and Engin. World, 

 38 {1913), No. 10, p. 488). — ^An analysis of Macrocystis pyrifera showing 1.65 

 per cent of potash in the fresh plant (87.02 per cent of water) is reported and 

 the fertilizing value and commercial possibilities of kelp are discussed. 



Commercial fertilizers and their use, G. S. Fraps {Texas Sta. Bui. 167 

 {1914), pp. 3-45). — This is a popular discussion of the subject, dealing par- 

 ticularly with the plant food requirements of different crops and how fertilizers 

 supply these requirements, the principal sources and nature of fertilizing mate- 

 rials, the preparation of fertilizers, the valuation and purchase of fertilizers, 

 methods of experimenting with fertilizers, and methods of using fertilizers on 

 different crops and soils, particularly those of Texas. 



Chemical analyses of licensed commercial fertilizers, 1913, F. W. Woll 

 and "W. H. Strowd {Wisconsi7t Sta. Circ. 49 {1914), pp. 17, fig. 1). — Guarantied 

 and actual analyses of fertilizers, including ground limestone and rock phos- 

 phate, offered for sale in Wisconsin during the year are reported and discussed. 



AGRICTJLTTJRAL BOTANY. 



Spore conditions in hybrids and the mutation hypothesis of De Vrles, 

 E. C. Jeffrey {Bot. Gaz., 58 {1914), No. 4, pp. 322-336, pis. 4).— The author 

 reports examining a large number of spore-bearing plants as well as numerous 

 higher plants, and foimd that spontaneous hybridization, while comparatively 

 rare among lower plants, is very common among the anglosperms. In such 

 families as the Rosacese and the Onagracese there are found to be grading 

 into each other recognized species and recognized hybrids, having in common 

 the character of partial or complete reproductive sterility, which is easily 

 recognized in the organization of the pollen. This is said to point to the 

 hybrid origin of these abnormal species. Species of this type, the author pro- 

 poses, should be called crypthybrids and include species of CEnothera, many 

 species of Epilobium, and probably those of Fuchsia. This addition, it is 

 claimed, must be recognized in connection with any investigation on the origin 

 of species based on such material as (E. lamarckiana, (E. Uennis, etc. 

 70903°— 14 3 



