148 NATURAL SCIENCE [March 



chemical relations and their extension to proteids and nucleins 

 is another of the problems of physiology which will contribute to 

 the main problem, the analysis of the constitution of living matter." 

 Physiologists who may desire to take up the study of this 

 fascinating but intricate subject may be glad to know that Messrs 

 Longmans, Green & Co. have just published a second edition of 

 Dr Eiloart's translation of Van't Hoff' s work, " The Arrangement of 

 Atoms in Space." This deals with the stereochemistry of carbon 

 and of nitrogen compounds, and contains an appendix by Professor 

 Alfred Werner of Zurich, on the stereochemical isomerism of in- 

 organic compounds. This edition has been thoroughly revised and 

 brought up to date, and contains a full index. The price is six 

 shillings and sixpence. Recommendation of such a classical work 

 is superfluous. 



Osmosis and Animal Electricity 



The passage of fluids through thin membranes, known as osmosis, 

 deserves even more attention than it has hitherto received, since it 

 enables us to understand many vital processes that would otherwise 

 seem to be inexplicable on purely physical or chemical grounds. 

 Again, to quote Dr Loeb, " Van't Hoff's theory of osmotic pressure 

 permits an application of the law of conservation of energy to a 

 class of phenomena to which this law was hitherto inapplicable, 

 namely, the phenomena of growth, functional adaptation, secretion, 

 absorption, and even pathological processes, such as oedema. The 

 physiologists who thought that the blood pressure determined 

 secretion could not understand why secretion took place under a 

 higher pressure than the blood pressure. Comparative physiology 

 shows that secretion does not depend upon circulation, and the 

 theory of osmotic pressure indicates that the osmotic pressure in the 

 cells is more than twenty times as high as the l^lood pressure. The 

 work of secretion is done by osmotic pressure and not by blood 

 pressure. A prominent physiological chemist has become a vitalist 

 because he could not explain why the secretions differ from the 

 blood from which he thinks they are formed. He overlooks, among 

 others, the fact that the protoplasm possesses the quality of semi- 

 permeability, which means that it allows certain substances to pass 

 through and others not." 



" The theory of the dissociation of electrolytes is of fundamental 

 importance in the analysis of the constitution of living matter. 

 Pharmacology will feel its influence most directly. Everything 

 seems to indicate that the specific physiological effects of inorganic 

 acids are due to the number of positively charged hydrogen ions in 

 the unit of solution, and the specific physiological effects of alkalies 

 to the negatively charged hydroxyl ions. But the universal bearing 



