AGRICULTURAL BOTANY. 727 



facilities of tbis laboratory. Uiiown as tbe Desert Botanical Laboratory, are 

 described, togetlier witli sonic of tiie investigations in progress. These inclnde 

 studies on tbe influence of altitude and climatic factors upon vegetation — 

 acclimatization, movements, and distribution of desert vegetation, studies on 

 trans]iiration, root habits of jilants. soil and air temperatures, etc. 



Report of the department of experimental evolution, Cold Spring Harbor, 

 New York, ('. P.. 1 >avi:.ni'()kt {<'ani<(iic lust. \\'(isJiiiii/l(Jii )'(ar lioolc. .7 {UIIKI}, 

 pp. 9.i-J0.'). pl.^. S. fi(j. 1). — An account of tbe investigations in jirogress under the 

 Carnegie Foundation at the laboratory of experimental evolution. Cold Sjiring 

 Harbor, Xew York. Among the principal subjects are tbe inheritance of charac- 

 teristics, unit characteristics, role of selection, origin of new characteristics, 

 and identity of evolutionary processes in plants and animals. 



The author states that the policy of the laboratory is not to seek after prac- 

 tical results, but to confine the investigations to a study of the laws of evolution 

 and the various princii)les underlying them. After describing the equipment of 

 the laboratory, brief in-eliminary reports are given on a number of tbe 

 investigations. 



Elementary species in agriculture, IL de Vries (Separate from Proc. A^ner. 

 Phil. ,S'oc.. //J (1906), pp. l.'i9-lo6). — In a paper presented before tbe Philosoph- 

 ical Society the author discusses the relative merits of plant breeding by the 

 selection of unit characters and by the method pursued by some breeders 

 wherein the resultant crop is secured by a prolonged system of elimination. 

 He claims that selection by individual seed is much more successful than where 

 the selection is made of a number of individuals, which must necessarily include 

 some that are not pure races. Incidentally tbe author calls attention to the 

 fact that the breeding experiments carried on by N. H. Nilsson and W. M. Hays 

 corroborate bis theory of evolution by mutation. 



The existence of a semipermeable membrane inclosing the seeds of some 

 Gramineae, A. ,T. Prown (Aim. Hot. \Loii(toii\. 21 (1907). No. 81. pp. 79-87). — 

 While investigating tbe conditions governing the absorption of water by tbe ripe 

 grains of certain cereals, the author made some experiments with tbe grain of 

 a variety of barley, which indicated that the embryo and endosperm of this 

 grain are contained within a semipermeable covering. 



A number of experiments were carried on to test the permeability of this 

 membrane to water, iodin solution, and various salt solutions, and it was found 

 that tbe embryo and endosperm are inclosed within an envelope through which 

 water and iodin readily pass to the interior of tbe grain, but acids and salt solu- 

 tions are retarded. To test whether tbis envelope of tbe barley grain was due 

 to living protoplasm or not. seeds were treated with boiling water." after which 

 they were placed in a normal sulphuric-acid solution for 48 hours. vSubsequent 

 investigation showed that there was no penetration by the acid, indicating that 

 the semipermeable pi'operty of the covering of tbe grain is not due to the action 

 of living protoplasm. It seems probable that this property centers in the testa, 

 but whether the property is confined to onl.v one of the la.vers has not been defi- 

 nitely determined. 



Experiments with oats, wheat, and rye showed that they all possess a similar 

 semipermeable covering. 



The culture of the excised embryos of barley on nutrient solutions con- 

 taining nitrogen in different forms (Trans. Guinness Research La1>.. 1 

 (1906), pt. 2, pp. 288-299). — Embryos of barley excised after germination were 

 grown on different nutrient solutions containing a number of forms of nitrogen 

 to determine the value of nitrogen as a nutrient for these plants. 



In the experiments the actual increase in dry weight during growth, as well 



