FIELD CROPS. 727 



directly upon the formation of essential oil in the leaves, flowers, and fruits, 

 such production being retarded by an increase of illumination, and the optimum 

 being reached in subdued daylight. The optimum light intensity for oil pro- 

 duction is, moreover, below that for production of dry matter. Some bearings 

 of these facts are discussed. 



Artificial photosynthesis by means of dxlorophyll, W. J. V. Ostebhout 

 {Abs. in Science, n. scr., Ji2 {1915), No 1011, p. 68).— The author states that if 

 Schryver's test for formaldehyde is specific, experiments show that formalde- 

 hyde produced from chlorophyll acting in the presence of carbonic acid in sun- 

 light is due to the decomposition of the chlorophyll and not to photosynthesis, 

 as has been supposed to be proved. Other pigments, as methyl green, iodia 

 green, and a variety of other stains, exposed to sunlight under the same con- 

 ditions as chlorophyll, also give the test for formaldehyde. From this it is 

 considered that artificial photosynthesis by means of sunlight has not yet been 

 accomplished. 



The efEects of electrolytes on oat seeds, F. Plate (Ann. Bot. [Romel, 12 

 {1914) r No. 3, pp. 261-34S). — After a review of reports by others on related 

 studies, the author gives in considerable detail the results of his own more 

 recent work (E. S. R., 30, p. 228; 33, p. 521). The numerous organic and inor- 

 ganic compounds employed arc arranged in seven general groups according to 

 their observed relations as noted in regard to their absorption and their efEects 

 on the germination and development of the seeds. 



A new device for sterile preservation of seeds, M. Plaut {Ber. Deut. Bot. 

 Gesell., 32 {1914), No. 7, pp. 466-411, figs. 3). — A description is given of a com- 

 bination cap of wire gauze and cotton wool for closing vessels intended to con- 

 tain seeds for preservation, experimentation, etc. This is expected to give at 

 low cost complete protection with safety, convenience, and ease of manipulation. 



The heredity of fasciation in Bunias orientalis, R. Pieotta and M. Puglisi 

 {Ann. Bot. [Rome], 12 {1914), No. 3, pp. 345-360, pis. 6).— As a result of the 

 preliminary study here described, the authors consider the tendency to fascia- 

 tion in B. orientalis {Lwlia orientalis) to be hereditary. 



Flora of New Mexico, E. O. Wooton and P. C. Standlet {JJ. S. Nat. Mus., 

 Contrib. Nat. Herbarium, 19 {1915), pp. 75^).— This flora of New Mexico is 

 based largely upon the authors' collections, supplemented by all the available 

 material to be found in the principal herbariums of the world. Both the authors 

 were for a time connected with the New Mexico Experiment Station, from 

 which point their collecting work was largely done. 



About 3,000 species of flowering plants and vascular cryptogams are included 

 in the publication. Keys are given to the genera and species so that this flora 

 may be used as a field manual in the region covered. 



Tropical North. American species of Panicum, A. S. Hitchcock and Agnes 

 Chase {TJ. S. Nat. Mus., Contrib. Nat. Herbarium, 17 {1915), pt. 6, pp. XII + 

 459-539, figs. 139).— In a preceding paper (E. S. R., 24, p. 432) the authors 

 presented a revision of the North American species of Panicum. The present 

 contribution is the result of further studies of the tropical species which were 

 not fully treated in the previous publication. Keys are given for all the tropical 

 species, although descriptions are not always included. The authors list 116 

 species and 3 subspecies, 9 of which are described as new. 



FIELD CROPS. 



On a criterion of substratum homogeneity (or heterogeneity) in field ex- 

 periments, J. A. Harris {Amer. Nat., 49 {1915), No. 583, pp. 430-454, figs. S).— 

 In this article the author points out the need of some generally applicable meas- 



