220 EXPEEIMEJJ'T STATION RECORD. [Vol.41 



Geobotany of the Santa Lucia Mountains, F. Shreve {Carnegie Inst. Wash- 

 ington Year Book, 11 {1918), pp. 18, 19). — ^An examination has been made of the 

 Santa Lucia Mountain region in California, which embraces chiefly or entirely 

 the distributional areas of Pinus radiata, Abies venusta, Cupressus macrocarpa, 

 and C. govcniana, as well as the southernmost localities of Sequoia SGn\pcrvirens 

 and a number of its associates. While geomorphic movements undoubtedly lie 

 at the basis of the present distributional features, a good opportunity is offered 

 for investigation of the factors controlling reproduction and life history of all 

 these endemic forms. 



The vegetation of an imperfectly drained desert valley, F. Shreve {Car- 

 negie Inst. Washington Tear Book, 11 {1918), pp. 16-18). — Field and laboratory 

 work has been inaugurated with the view of investigating the role played 

 by the soil in determining tlie differences of vegetation which characterize the 

 Avra Valley of Arizona. The fact that this valley is not undergoing the nor- 

 mal course of physiographic development, being subject to frequent checks 

 and reversals of such development, makes it a particularly suitable area for 

 Investigation of such a problem. 



Isolation and specific change, E. W. Sinnott {Brooklyn Bot. Gard. Hem., 1 

 (1918), pp. J/Jf^-^-'fl). — Data are presented and discussed to show that isolated 

 regions are characterized by the presence of large numbers of local, or endemic, 

 genera and species. 



Endemism was not equally distributed among the plant gi'oups in the insular 

 floras investigated. The local species and genera were rare among vascular 

 cryptogams and glumaceous monocotyledons but very common among petalol- 

 deous monocotyledons and dicotyledons, this fact supposedly indicating that 

 the environment, whether acting directly or through natural selection, has not 

 been the determining factor in the development of endemic forms. Those 

 groups which are poor iu endemics are predominantly self-fertilized, those 

 which are rich in endemics predominantly cross-fertilized, these facts suggesting 

 that hybridization has been the predominant factor in the development of 

 these new forms. Isolation is, therefore, regarded not as a factor which, by 

 providing a simple, limited, and peculiar environment, produces local species 

 and genera, but merely as a factor which, by prohibiting dispersal, maintains 

 the endemic character of local tjioes whicli have originated through other 

 causes. 



Osmotic concentration of tissue fluids in relation to geographical distribu- 

 tion, J. A. Harris {Carnegie Inst. Washington Year Book, 11 {1918). pp. 86, 

 81). — This work, continued along lines previously indicated (E. S. R.. 40, p. 

 130), has shown that the osmotic concentration of the tissue fluids of epiphytic 

 Bromeliaceje, Orchidacese, Piperacea?, and Gesneraceje is lower than that of 

 the terrestrial vegetation. The problem of the osmotic concentrntion of the 

 tissue-fluids of cryijtogamic epiphytes is to be made a subject of further study. 



On the osmotic concentration of the tissue fluids of phanerogamic epi- 

 phytes, J. A. Harris {Amer. Jour. Bot., 5 (1918), No. 9, pp. .J90-560).— This is a 

 more extended account than that above noted. 



Endurance of extreme conditions and its relation to the theory of adapta- 

 tion, W. .J. V. OsTERHouT {Amer. Jour. Bot., 5 {1918), No. 10, pp. 501-510, fig. 

 1). — The author reports that a species of Tradescantia lived for nearly two 

 years without soil or water, growing vigorously afterwards in a saturated at- 

 mosphere, and was finally placed under water for a month, being alive at the end 

 of the experiment. It is thought that the explanation of such cases must be 

 sought in physical or chemical conditions of the protoplasm which arise without 

 reference to direct adaptation, and it is suggested that the same kind of ex- 

 planation may apply to many cases which aro now regarded as adaptations. 



