SCIENCE 



Friday, March 21, 1913 



CONTENTS 



Avogadro's Law and the Absorption of 

 Water by Animal Tissues in Crystalloid 

 and Colloid Solutions: Pkopessob Jacques 

 LoEB 427 



The Spread of the Brown-tail and Gypsy Moth 439 



Tlie New Geological Survey Building 4'I0 



Scientific Notes and News 440 



University and Educational News 445 



Discussion and Correspondence: — 



The Yellowstone: Professor W. S. Frank- 

 lin. Alleghany Valley Erosion: Edward 

 H. Williams, Jr., Academic Freedom: Pro- 

 TESSOB J. E. Creighton 446 



Scientific Boohs: — 



Alder and Rancoch on British Tunicata: 

 Professor Wm. E. Ritter. Miller's List 

 of North American Land Mammals: J. A. 

 A. Euler's General Chemistry of the En- 

 zymes: Professor C. S. Hudson 451 



Special Articles: — 



Mitochondria in Ascaris Sex-cells: Edward 



E. Wildman 455 



The American Association for the Advance- 

 ment of Science: — 



Section E — Geology and Geography: Pro- 

 fessor Geo. F. Kay 456 



Societies and Academies: — 



The American Mathematical Society: Pro 

 FEssoR p. N. Cole. The Academy of Sci 

 ence of St. Louis: Professor George 

 James. The Botanical Society of Washing 

 ton: Dr. C. L. Shear. Fhilosophical So 

 ciety of the University of Virginia: Pro 

 FESSOR Wm. a. Kepneb 



460 



MSS. intended for publication and books, etc.. intended for 

 review should be sent to Professor J. McKeen Cattell, Garrison- 

 On-Hudson, N. Y. 



AVOGADBO'S LAW AND THE ABSORPTION 



OF WATER BY ANIMAL TISSUES IN 



CRYSTALLOID AND COLLOID 



SOLUTIONS ' 



I. STATEMENT OF THE PROBLEM 



Fifteen years ago, on an occasion sim- 

 ilar to this, the writer stated that if the 

 constitution of matter is the main problem 

 of the physicist the constitution of living 

 matter is the main problem of the biologist. 

 To-day I will discuss the applicability of 

 Avogadro's law, onj of the most funda- 

 mental laws underlying the constitution of 

 matter, to a group of life phenomena, 

 namely the regulation of the amount of 

 water in animal cells and tissues. Accord- 

 ing to Avogadro's law equal volumes of 

 gases at the same temperature and pres- 

 sure contain an equal number of mole- 

 cules; or, in other words: In the gaseous 

 state equal numbers of any kind of mole- 

 cules enclosed in equal volumes have the 

 same pressure at the same temperature. 

 This law was extended to solutions by 

 van't Hoff in the following form: All dis- 

 solved substances produce upon a mem- 

 brane which prevents their diffusion but 

 allows water to diffuse an osmotic pressure 

 equal to that which would be produced by 

 gaseous matter containing the same num- 

 ber of molecules in the same volume. 

 Combining Avogadro's and van't Hoff's 

 law we may state that the same number of 

 molecules of any kind of matter produce 

 at the same temperature and volume the 

 same pressure upon the walls which pre- 

 vent their diffusion. 



'Read by title in the Botanical Section of the 

 Cleveland meeting of the Society of Amerieaa 

 Naturalists, December, 1912. 



