1020] AGRICULTURAL BOTANY. 223 



The n-^notheras as niicloar chi moras, J. P. Lotsy, H. N. Kooiman, and 

 M. A. J. (JoKDKWAAGKN (Gciu'tUa [Tlic Ilnt/uc], 1 {191D), Xo. 1, pp. 7-69, fig. 

 1). — This is an account of a study durini: 1018 of tlie results of intercrossing 

 among species of CEnothera, based on the hypotliesis that the genus is, as 

 regards its origin, a nuclear chimera. This hypothesis is considered to be 

 supporttxl by the extensive data hero presented. 



Sonic applicntions of the quadrat method, IF. A. Gi.eason {Bill. Torrcy Hot. 

 Club, .',7 {1920), Xo. 1, pp. 2i-35).— This is a discussion of the so-called quadrat 

 method as used in ecological study, by which is meant the intensive study of 

 the vegetation and environment of a definite and limited area known as a 

 quadrat, or of a given number of such areas, in order to gain a comprehen- 

 sive knowledge of the vegetation as a whole. 



The values and errors pertaining to such a system are discussed. An account 

 is given of the method employed and of the work done by the author during 

 1911-1915 at the Biological Station of the University of Michigan. 



Experience has shown that better results are obtained if the plats are not 

 contiguous, but judiciously distributed over the association. This method is 

 appraised in comparison with others which are noted. 



Ecology of Tilia americana. — I, Comparative .studies of the foliar trans- 

 piring power, J. E. Ciubhs (Hot. Gaz., 68 {1919), Xo. J,, pp. 262-2S6, fi(js. i.i). — 

 An account giving ecological and geographical details of studies on transpira- 

 tion in T. americana states that cobalt chlorid standardized paper was found to 

 be suitable for comparative studies in the relative transpiring power of leaves 

 In the field. 



The daily march of transpiration in Tilia varied greatly for the same leaf on 

 different days, being influenced by relative humidity, temperature, light inten- 

 sity, soil moisture, and presumably soil temperature. The foliar transpiring 

 power of Tilia varied considerably in dune environments, the transpiring power 

 being directly proportional to the relative exposure. The morning rise in the 

 daily march was more rapid on the open sand, reaching here its maximum one 

 to two hours earlier than in forested situations. 



Where relative transpiration tends to develop a single mode past midday, the 

 maximum is said to have shown a tendency to coincide with the maxima of 

 temperature, relative humidity, and evaporating power of the air. The foliar 

 transpiration index was influenced less by wind currents than was the porous 

 cup atmometer. A second and lower mode may be developed about 4 p. m. No 

 evidence of visilile wilting occurred in Tilia on the open sand, though the so- 

 called incipient drying was a common feature. The amount of growth water in 

 the soil apparently has very little influence on the transpiration index uniess it 

 Is reduced to the wilting coefficient. 



The water economy of maritime plants, T. G. Hill {Sci. Prog. [London'\, 

 *H (1919), Xo. 53, pp. 60-SO, flg.^. 3).— In the pre.sent article an attenipt is made 

 to weave into a consecutive story the results obtained since 1904 in the botanical 

 department of University College, London, in connecti(m with the study of prob- 

 lems associated with the existence of maritime plants. Those as hoi-e presontod 

 include the action of sodium chlorid; adaptation to varying salinity; transpira- 

 tion; and absorption of water by aerial parts. Among the results and conclu- 

 sions which are detailed in their several connections, it is stated that in case of 

 Salicornia under natural conditions the crimson transpire more rapidly than do 

 the apple green plants; the plants, whether crimson or apple green, from mixed 

 sods transpire at a greater rate than do those of the same color from pure sods; 

 and crimson plants either from a pure or a mixed sod transpire more rapidly 

 187890"— 20 3 



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