THl^. PHYSIOl.OrjCAL ROLE OF WATF.R IN PLANTS. 



EnMONi) Gain, 



ProfiSKor of A<irirnl1ural I']nisiolo(ji/ and Chemistry, I'virersili/ of Nancii, France. 



Water i)lays an iin])ortant role in tlie growth of plants, and if we 

 consider the ])Ossibility of controlling its distribntion by means of irri- 

 gation, tlie practical interest attached to an exact stndy of its function 

 in ]dant growth becomes apparent. 



The qnestion is very complicated from a theoretical point of view. 

 If considered merely from the side of application of water, there are 

 many difficnlties due to the varying requirements of each of our culti- 

 vated plants. 



While morphologically plants of the same or even different species 

 nniy agree, the physiological characters are very dissimilar, and it often 

 happens that the i^liysiological requirements of varieties of the same 

 si)ecies are totally unlike. By selection and hybridization we are 

 enabled to produce races and varieties having very different character- 

 istics. In the process of acclimatization certain secondary morpho- 

 logical chaiacters are developed which are often retained by the plant 

 in its struggle to adapt itself to its surroundings. 



Gaston Bonnier,' of the .University of Paris, has shown the con- 

 vergence of morphological types under the influence of cold, due either 

 to latitude or altitude, and that plants upon mountain tops and in polar 

 regions have analogous structures. 



J.Vesque- has established the fact that inherited characteristics have 

 little to do with the adaptation of plants to drought and that there is 

 no genus, however small, all the species of which arc adapted in the 

 same degree to a given idiysical environment. Tiiis biological jirinciple 

 is cited to show the necessity for repeated experimental research in 

 order to elucidate the role of water in the growth of cultivated plants. 

 Consideration of it will also prevent too hasty generalization from con 

 elusions which pertain to a single species. Exact information is neces- 

 sary as to the species under experiment, as well as the variety and race, 

 also the country whence the seed, tubers, bulbs, etc., came. In regard 

 to reproduction by cuttings, the writer does not believe there is an 



'Rev. gou. Bot., G (1894), p. 505; Compt. Kend., 113 (1894), p. 1427. 

 ^L'iibsorption do I'eau et la transpiration, Ann. Soi. Nat. Bot., ser. (5, vol. 4, p. 89; 

 vol. 6,1). 169; vol. 9, p. 5. 



