488 



SCIENCE 



[N. S. Vol. XL. No. 1031 



nisse der Eechenkiinstler, by D. E. Smith; 

 Study's Konforme Abbildung einfach-zusam- 

 menhangender Bereicbe, by Arnold Emcb; 

 " Notes ; " and " New Publications." 



The July number of the Bulletin contains: 

 Eeport of the April meeting of the society in 

 New York, by F. N. Cole; Eeport of the 

 twenty-fifth regular meeting of the San 

 Francisco section, by Thomas Buck ; " The 

 ratio of the arc to the chord of an analytic 

 curve need not approach unity," by Edward 

 Kasner; "A Mersenne prime," by R. E. 

 Powers; Review of Osgood's Lehrbuch der 

 Funktionentheorie, by E. B. Van Vleck; 

 " Notes ; " " New Publications ; " Twenty-third 

 annual list of published papers; and Index of 

 Volume 20. 



The October number (Vol. 21, No. 1) of the 

 Bulletin contains : " On a small variation 

 which renders a linear differential system in- 

 compatible," by Maxime Bocher ; " The small- 

 est characteristic numbers in a certain excep- 

 tional case," by Maxime Bocher ; " On approxi- 

 mation by trigonometric sums," by T. H. 

 Gronwall ; " Note on the roots of algebraic 

 equations," by R. D. Carmichael and T. E. 

 Mason ; " Remarks on functional equations," 

 by A. R. Schweitzer ; " Shorter Notices ; " 

 Hadamard's Legons sur le Oalcul des Varia- 

 tions, Tome premier, by E. R. Hedrick; Bou- 

 troux's Principes de 1' Analyse mathematique. 

 Tome premier, by J. B. Shaw; Blumenthal's 

 Principes de la Theorie des Eonctions entieres 

 d'Ordre infini, by G. D. Birkhoff; Riesz's 

 Systemes d'Equations lineaires a une Infinite 

 d'Inconnues, Bowley's General Course of Pure 

 Mathematics from Indices to Solid Analytic 

 Geometry, and Fabry's Demonstration du 

 Theoreme de Fermat, by R. D. Carmichael; 

 Silberstein's Vectorial Mechanics, by E. B. 

 Wilson ; " Notes ; " and " New Publications." 



SPECIAL ARTICLES 



TITALITT AND INJURY AS QUANTITATIVE 

 CONCEPTIONS 



Although a fundamental conception of 

 physiology, the idea of vitality has not been 



very precisely formulated. This is not only 

 unfortunate from a theoretical standpoint, but 

 it also has practical disadvantages. The phys- 

 iologist often finds that the validity of his con- 

 clusions depends on selecting material of 

 normal validity for his experiments. When 

 he examines organisms for this purpose he is 

 too apt to find that all the tests of vitality 

 which he employs are uncertain or that at 

 best they lack the precision necessary for 

 quantitative work. 



An accurate method of measuring vitality 

 seems therefore to be needed not only for more 

 precise formulation of the conception itself, 

 but also for practical purposes. 



The investigations of the writer lead to the 

 conclusion that the vitality of a tissue is so 

 dependent on the maintenance of its normal 

 permeability that we may employ the permea- 

 bility of protoplasm as a sensitive and reliable 

 indicator of its vitality. We may therefore 

 obtain an accurate measure of the vitality of 

 a tissue by carefully measuring its perme- 

 ability. 



This may be accomplished by determining 

 the electrical resistance of living tissues. This 

 method is rapid and convenient for practical 

 use. It may be applied to pieces of detached 

 tissue or to the intact organism. 



The writer began the use of this method by 

 cutting disks from the fronds of the marine 

 alga, Laminaria saccharina, and measuring 

 their electrical resistance in a manner which 

 has already been described.^ Subsequently it 

 was found possible to measure the resistance 

 of intact fronds both of Laminaria and of 

 other plants by methods which will be de- 

 scribed in detail in a future publication. 



As the result of his experience with this 

 method the writer concludes that it is often 

 very difficult to judge of the condition of an 

 organism by its appearance. The tissues on 

 which experiments have been made were found 

 to be capable of losing much of their vitality 

 without betraying it in any way by their ap- 

 pearance. (This was particularly the case with 

 eel grass, Zostera, which retained its normal 

 green color and appearance for some days after 



1 Science, N. S., 35 : 112, 1912. 



