304 SCIENCE PROGRESS 



comparison be as simple as possible and also that it produce 

 good growth of the plants. He has made preliminary trials 

 with a three-salt solution (monopotassium phosphate, calcium 

 nitrate and magnesium sulphate, with a trace of ferric phos- 

 phate), which has given better results than the four-salt solu- 

 tions employed by Knop and by Tottenham. 



Ecology. — Much of the physiological work published nowa- 

 days is so intimately related to the ecology of plants as to be 

 almost or quite inseparable from that branch of botany, which 

 is making rapid strides and becoming something vastly 

 different from the perfunctory recording of plant communities 

 which passed for plant-ecology only a few years ago. Living- 

 ston {Plant World, 18), has contributed a comprehensive and 

 useful paper on the methods and results of measurement of 

 the evaporating power of the air — strictly speaking a branch 

 of meteorology, but one which has been chiefly developed by 

 plant-ecologists, and which promises results of the utmost 

 importance in the study of plant distribution. The same 

 author, with collaborators, has dealt (Carnegie Inst. Publ. 204), 

 in a similar manner with the water-relation between plant and 

 soil, and with the water-supplying power of the soil as indicated 

 by osmometers ; this double memoir and the Plant World 

 paper are of the greatest value to ecologists. Shreve (Carnegie 

 Inst. Publ. 199) gives an elaborate account, with very fine 

 collotype plates, of the vegetation of the mountain rain-forests 

 of Jamaica, including, among many other interesting matters, 

 some experimental data which appear to show that hydathodes 

 (water-glands), drip-tips, and other supposedly adaptational 

 features of tropical rain-forest plants fail entirely to function 

 in the manner attributed to them by writers who have given 

 teleological explanations unsupported by experimental evidence. 

 Miss Delf (Journ. Ecol. 3), in an extremely useful critical dis- 

 cussion of the structural and physiological ideas expressed by 

 the term " xerophily " (adaptation of plants to inadequate 

 water-supply or excessive water-loss), deals in a very similar 

 manner with the widely prevalent but largely false views 

 which have gained vogue through hasty generalisation and 

 facile interpretation of function in terms of structure ; her 

 paper is extraordinarily useful and brings together a large amount 

 of recent work in plant physiology and ecology focussing on 

 the problem dealt with. That British botanists are doing 



