350 



SCIENCE. 



[N. S. Vol. IV. No. 89. 



The author described some preliminary- 

 work carried out in connection with the 

 determination of the dielectric constants 

 of liquids. 



The Influence of a Static Charge of Electricity 

 on the Surface Tension of Water : ^y Ed- 

 ward L. Nichols and John Anson 

 Clark. 



The authors used a dropping apparatus 

 for determining the surface tension, and a 

 novel electrometer for measuring E. M. F. 

 This electrometer consisted of a light con- 

 ducting sphere suspended by a long con- 

 ducting fibre near a large plane plate. The 

 movement of the sphere was observed by 

 means of a telescope. 



Determination of the Specific Heats of Nitrogen 

 by Adiabatic Expansion : By W. S. Frank- 

 lin and L. B. Spinney. 

 The authors pointed out the fact that of 

 the four quantities E, (in the equation 

 pv = Iit), K, 0^ and G^ associated with a 

 gas only two are independent ; and they 

 described some incomplete experiments for 

 the indirect determination of C^. 



The Analysis of Vowel-sounds, by Means of the 

 Sympathetic Vibrations of a Rigid Body: 

 By L. B. Spinney.^ 



The author described the manner of 

 mounting a light mirror so as to vibrate 

 with sound waves impinging upon it, and 

 exhibited a number of photographic trac- 

 ings. 



Polar and InterpolarEffects of the Galvanic Cur- 

 rent on Living Animal Tissues : By C. P. 

 Hart. 

 Description and Exhibition of a Portable Appa- 

 ratus for Recording Curves of Alternating 

 Currents and Electro-motive force : By H. J. 



HOTCHKISS. 



The author exhibited the apparatus, and 

 also, some photographic tracings taken by 

 means of it. 



The discussion of Nomenclature and 

 Units was made a special order for the last 



Sectional meeting, but on account of lack 

 of time it was deferred and made a special 

 order for the meeting of next year. 

 Iowa State College. W. S. Franklin. 



TRE PHYSIOLOGY OF COLOR IN PLANTS. 



Since the preparation of my recent sum- 

 mary of the uses of color in plants* the 

 work of Stahl in the botanic garden at 

 Buitenzorg has been published,f by which 

 some of the current conclusions are seri- 

 ously modified. 



I have pointed out in the paper cited 

 above that the theories concerning the re- 

 lations of plant colors to animals are by no 

 means on a secure basis, and Stahl by a 

 large number of experiments in which red 

 and green leaves were fed to snails, rabbits, 

 antelopes, etc., finds that the choice of food 

 depends on the degree of hunger of the 

 animal to a much greater extent than on 

 the color of the plants eaten. He con- 

 cludes that in no instance is it placed be- 

 yond doubt that color areas have been de- 

 veloped as a ' warning ' to serve as a pro- 

 tection against animals, but is disposed to 

 regard the so-called warning devices as ac- 

 cidental. 



Because of the prevailing acid reaction of 

 red leaves, this author uses the term 'Eryth- 

 rophj^U' to denote the reddish coloring mat- 

 ter, instead of 'Anthocyan.' So far as its 

 physical qualities are concerned, he con- 

 firms the view of Engelmann that its spec- 

 trum is complementary to that of chloro- 

 phyll. He does not, therefore, agree with 

 the theory of Kerner that color layers may 

 serve as a protection of the chlorophyll 

 against intense sunlight, J but formulates 

 an extended and modified statement of 

 Pick's conclusions, § in which he sug- 



* MacDongal : Physiology of Color in Plants. Pop. 

 Sci. Monthly, May, 1896. 



fUeber bunte Laubblatter. Ann. d. Jard. Bot. 

 Buitenzorg, 13: 137-216. 1896. 



X Pflanzenleben, 1 : 364. 1890. 



§ Bot. Centralblatt, 16: 1883. 



