486 



SCIENCE 



[N. S. Vol. XXXVIII. No. 979 



in orderly form and discussing as it does a vast 

 amount of material of observation, is the 

 pointing out of gaps in available data. The 

 pages of these " studies " raise numerous ques- 

 tions which must be settled in order that the 

 ■whole fabric of luminescence theory may be 

 further extended. Undoubtedly many of the 

 questions so raised will be worked out in the 

 same laboratories from which the present re- 

 searches have been issued. 



Even thus far the work represented in the 

 present memoir constitutes a most noteworthy 

 series of researches in the general field of 

 luminescence. Not only the care and patience 

 with which the observations have been made, 

 but much more the experimental acumen with 

 which the methods and materials have been 

 chosen and the illuminating discussions of 

 theoretical character, all contribute to give 

 these researches a place beside those of the 

 middle of the past century by which E. Bec- 

 querel blazed the way into this wonderfully 

 interesting region. Eecent developments in 

 physics attach much more of importance to the 

 phenomena of luminescence than could possi- 

 bly have been foreseen in those earlier years, 

 and it seems certain that further develop- 

 ments, in this and allied branches of physics, 

 will greatly enhance the value of the region as 

 a field for research. 



F. E. Kester 



SPECIAL ARTICLES 



NON-ELECTROLTTES AND THE COLLOID-CHEMICAL 

 THEORY OF WATER ABSORPTION 



The colloid-chemical theory best explains 

 at the present time the absorption of water by 

 protoplasm under various physiological and 

 pathological conditions. The laws governing 

 the absorption of water by such simple protein 

 colloids as fibrin and gelatine, are point for 

 point identical with those which we have 

 known to govern the absorption of water by 

 cells, tissues, organs, or the organism as a 

 whole. Thus fibrin and gelatine swell more 

 in any acid solution than in distilled water, 

 while protoplasm does the same. The addition 

 of any salt to the acid solution reduces the 

 amount of this swelling, and this the more the 



higher the concentration of the salt. The 

 same holds for protoplasm. At the same con- 

 centration different salts arrange themselves 

 in a characteristic order in this regard. The 

 same order is observed in protoplasm. 



In this way it has been possible to explain 

 without contradiction not only all those phe- 

 nomena which are ordinarily said to prove the 

 tenability of the laws of osmotic pressure for 

 the processes of absorption and secretion, as 

 observed in protoplasm under various patho- 

 logical and physiological circumstances, but 

 also the notable exceptions in behavior, which 

 no one believes explainable on the osmotic 

 basis. 



In the study of fibrin and gelatine, it was 

 found that various non-electrolytes, such as 

 sugars and alcohols, are relatively ineffective 

 in reducing their swelling in the presence of 

 any acid. Adherents to the osmotic theory of 

 water absorption have made this statement 

 read, entirely ineffective; and, because certain 

 non-electrolytes bring about shrinking effects 

 in various cells and tissues, have seen in this 

 a valid reason for rejecting the dominant im- 

 portance of the colloids and their state in 

 determining the amount of water held by 

 protoplasm. 



During the past year a systematic study of 

 the effect of various non-electrolytes on the 

 swelling of gelatine and fibrin has been un- 

 dertaken. The effect of non-electrolytes 

 upon these is identical with their effect upon 

 protoplasm. The various organic compounds 

 thus far studied (saccharose, dextrose, levulose 

 glycerine, ethyl alcohol, methyl alcohol, propyl 

 alcohol, propylene glycol, etc.) all decrease 

 the swelling of gelatine or fibrin in either 

 neutral or acid solution, and this the more 

 the higher the concentration of the added 

 compound. When equally concentrated (equi- 

 molecular) solutions are compared the sugars 

 are found to be more effective than the alco- 

 hols in this regard. The same is true of pro- 

 toplasm. The sugars among themselves are 

 unequally effective in dehydrating protein 

 colloids, and in a similar way are they un- 

 equally effective in dehydrating living tissues. 



