RECENT ADVANCES IN SCIENCE 559 



is that the extracted long-glumed type exhibited a smaller range 

 and diminished average length, as compared with the parent, 

 T. polonicum. 



Miss I. Sutton contributes to the same journal a report on 

 tests of self-sterility in plums, cherries, and apples. Lists are 

 furnished of sixteen self-sterile plums, five partly self-fertile, 

 and eighteen self-fertile varieties. The majority of the cherries 

 proved self-sterile (17 vars.), three were self-fertile, and two 

 partially so. Of the apples experimented upon, viz. thirty-four, 

 eight proved self-sterile and sixteen self-fertile. The results 

 obtained are not inconsistent with the view that self-sterility 

 is a recessive and the partially self-sterile individuals may be 

 heterozygous. Except for the " Coe " varieties of plum and 

 " Jefferson," which appear to be sterile with other pollen be- 

 sides their own, the pollen of any other variety would appear 

 to serve in the case of self-sterile individuals. 



Ecology. — In the June number of Soil Science, M. I. Wolkoff 

 contributes a paper of fifty-nine pages dealing with the influence 

 of ammonium sulphate on the germination and growth of 

 barley. It is impossible to summarise all the results obtained, 

 many of which are of agricultural rather than ecological interest. 

 The following conclusions are of general significance. The 

 osmotic concentration of the soil solution subsequent to the 

 addition of a fertiliser becomes important when there is a 

 considerable reduction of the water content below the optimum. 

 The rigidity of straw is regarded as dependent upon a proper 

 balance in the nutrient solution. With increase of yield there 

 is a decrease in the amount of water utilised in the production 

 of each grain of dry weight. In the same journal for July 

 R. E. Stephenson discusses methods of determination of soil 

 acidity in which, however, that devised by Hutchinson and 

 MacLennan is ignored. 



Determinations of the osmotic concentration of tissue 

 fluids in various epiphytes have been made by J. A. Harris 

 (Amer. Jonrn. Bot. Nov. 191 8). The results (3*3-5*6 atmo- 

 spheres) show a far lower osmotic concentration than in terrestrial 

 vegetation. Estimations from the Jamaican montane rain 

 forest gave concentrations which were only from 37-60 per cent, 

 that of the ordinary herbaceous flora and from 28-45 per cent, 

 that of the ligneous vegetation. 



Prof, Osborne {Trans. Roy. Soc. S, Australia, 191 8), in re- 



