656 



SCIENCE 



[N. S. Vol. XLI. No. 1061 



operating that all functions are sustained in 

 effective cooperation. Not only do the differ- 

 ent salts mutually offset each other's physio- 

 logical deficiencies, but they are able to offset 

 the usually harmful action of the solvent. 

 Loeb has found an interesting experimental 

 subject in Fundulus, a fish which is at home 

 not only in the complete mixture, but which 

 likewise survives for a time in distilled water. 

 In the case of organisms which survive indefi- 

 nitely in distilled water, it is likely that many 

 do so largely by virtue of the salts contained 

 in their ovsti bodies. In general it appears that 

 pure water extracts ions more or less rapidly 

 from many plants and animals, and in case the 

 experimental organism in question is of con- 

 siderable size and the volume of water suffi- 

 ciently limited the medium may easily get 

 enough ions from the experimental plant or 

 animal to offset the harmful action of the pure 

 water. The ability of Fundulus heieroclitus 

 to part with considerable quantities of salts 

 to fresh water without immediately evident 

 injury has been shovpn by Sumner. This fish 

 is, however, hardly typical of marine organ- 

 isms as a whole. In the red algse, incomplete 

 mixtures are injurious, as in Fundulus, but, 

 unlike it, they are promptly killed by distilled 

 water, which for them must be listed with the 

 other constituents which, taken individually, 

 act as fatal poisons. In this case, the mix- 

 ture of salts is required to antagonize or 

 efface the action of the water. A harmful ac- 

 tion has been shown to characterize distilled 

 water when used as a medium for various 

 land plants as well, and to antagonize or efface 

 this harmful action certain mixtures of salts, 

 strikingly reminiscent of sea water in many 

 important points, the so-called nutrient solu- 

 tions, were long since devised by Knop, Sachs 

 and others. It has been shown more recently 

 by Osterhout and others that the so-called 

 nutrient salts are toxic to land plants when 

 taken individually in much greater dilution 

 than has been generally supposed. 



In both sea water and the more or less dilute 

 nutrient solutions present in the soil, normal 

 life is sustained as a rule only in mixtures of 

 proper proportions and necessary concentra- 

 tion. Since salts are required in both cases 



to overcome the harmful action of pure water, 

 as well as that of the salts themselves, there 

 seems to be no reason to seek to limit the use 

 of the term " balanced solutions " in the man- 

 ner suggested by Loeb and Osterhout. Unless 

 we admit that malnutrition due to a deficiency 

 in nutrient salts is a form of toxicity excited 

 by the substances present, we can hardly escape 

 the alternative proposition that the missing 

 salts are injurious in absentia. 



EoDNEY H. True 

 BuKEAu OF Plant Industry, 

 U. S. Dept. op Agriculture 



ON THE OSMOTIC PRESSURE OF THE JUICES OP 

 DESERT PLANTS 



In 1907 Drabble and Drabble^ argued from 

 a series of plasmolyzations of the leaf cells of 

 a number of British plants from a range of 

 habitats that physiological dryness of the 

 substratum is the primary factor in the de- 

 termination of the osmotic strength of the 

 contents of the leaf cells of flowering plants. 

 About four years later Fitting^ applied the 

 plasmolytie method in an extensive reconnais- 

 sance physiological study of the vegetation of 

 the rocky peaks and slopes of the Chaine de 

 Sfa and the adjacent lowlands, comprising 

 concentrated salt marsh and arable oasis. 

 Here he reports some enormously high con- 

 centrations of cell sap, such indeed as would 

 'theoretically give pressures of over 100 at- 

 mospheres if confined in suitable semiperme- 

 able membranes surrounded by pure water. 



The results of these two papers force upon 

 one the conviction that observations of the 

 concentration of the cell sap may form a legit- 

 imate, and indeed essential, feature of com- 

 prehensive and thoroughgoing ecological or 

 phytogeographical study. 



One must note, however, that the number 

 of observations from each habitat studied by 

 Drabble and Drabble was small, and that their 

 maximum intensity of dryness was not very 

 great. Again, there is no satisfactory series 

 of determinations of the osmotic pressure of 

 the sap of mesophytic plants to serve as a 



1 Drabble and Drabble, Bio.-Chem. Jour., 2 : 

 1907. 

 a Fitting, Zeitschr. f. Bot., 3 : 1911. 



