672 



NA TURE 



[Novi 



ai 



pressure ; one theory \\ ' been advanced to 



rv..i:.ii. tlii. w.is tliat th- !« alveolus acted as 



ittr.u ted lliiul from the blood, but 

 1!^ still in somewhat of a dilemma, 

 s^nic ' '•' tbc red blood corpuscles, api>ear to 



linvc II ^t their Hurfaces. but others do not ; 



if an auKJ . uicfl with an intra-vitam dye, the 



dve does ix mto the surroumling water when 



the surface t)t t!ic aiiurba is punctured. 



Prof. F. G. Donnan spoke of membranes from the 

 physico-chemical aspect, but exhibited a good deal of 

 sympathy and interest in the biological side of the 

 •ion, which he described as one of the most 

 i.int issues concerned with these physico- 

 i in iiin,al studies. The fact that membranes might be 

 living structures might alter all physico-chemical con- 

 ceptions, particularly those based on the study of 

 states of thermodynamic equilibrium. Living organ- 

 isms utilised an environment not in such an equili- 

 brium, were transformers and consumers of free 

 energy, and environmental eciuilibrium meant non- 

 activity and eventual death. Energy potentials 

 might run up in one place and down in another, so 

 that interpretations would be difficult. After re- 

 ferring to the thermodynamic aspect of osmotic 

 pressure. Prof. Donnan reviewed some of the theories 

 which had been advanced in explanation of the pro- 

 perties of membranes. The sieve theory, according to 

 which a semi-permeable membrane acted merely as a 

 sieve, was rather discredited : some form of adsorp- 



tion theory seemed more attractive ; for 1 

 substance is negatively adsorbed, it will 

 from the walls of the pore, so that pi; 

 passes through. As a modification ' 

 various views of ionic adsorption wl. 

 of explaining many facts. The form.; 

 holtz double layer on the walls of the ; 

 explain why the mobility of one ion can 

 more than that of the other. Different cui 

 tions of electrolyte on the two sides, or a d; 

 mobility of ions, would cause a flow by 

 electro-endosmosis. The alteration effect* 

 liquid potentials when a membrane wa-- 

 might also Iw explaine<l on similar lines, 

 paper contributed to the di.scussion by D; ... w. .v. 

 Pndeaux also dealt with membrane {>otentiaIs con- 

 sidered as diffusion potentials.) The ttnxln. t <.f ilir- 

 activities of two ions on either side 

 permeable to both were the same- : 

 planation of the facts of membrane • 

 (Donnan equilibrium), and is of consideral 

 ance to physiology. The explanation of diifcrciitial 

 permeability, as given by Meyer and Overton, was 

 that one of the constituents was soluble in the sut> 

 stance of the membrane, while the other was not 

 this view is not acceptable to physical ch< 

 Also, the suggestion of Clowes, that the rev< : 

 phase in a membrane of emulsoid structure niigni 

 explain a changed permeability of membranes, cannot 

 be entertained. 



Science and Social Service. 



THE presidential address delivered by Sir George 

 H. Knibbs at the New Zealand meeting of the 

 Australasian Association for the Advancement of 

 Science in January 1923, entitled " Science and its 

 Service to Man," reviews the recent advances in the 

 fields of astronomy, relativity, atomistics, radio- 

 activity, spectroscopy, and various branches of 

 chemistry, including biochemistry, metallurgical 

 chemistry, and a number of technical applications of 

 synthetic chemistry. There is a brief notice of the 

 Rutherford - Bohr theory of atomic structure, and 

 the properties of colloids and of vitamins are dis- 

 cussed, together with the functions of the ductless 

 glands, and their relation to human development. 

 The following extracts from the address are of par- 

 ticular interest : 



The highest product of civilisation is not the 

 mere maintenance of man on the planet, but such 

 maintenance as makes him a student of that vast 

 universe of which physically he forms so utterly 

 insignificant a part — a student, developing faculties 

 by means of which he can appreciate beauty, magni- 

 ficence, majesty, and, indeed, the whole range of 

 things spiritually apperceived or intellectually grasped 

 — a student capable of solving the most apparently 

 hopeless problems. 



Nevertheless, in addition to these intellectual gifts, 

 the proper study of science may result in im- 

 portant material advantages. At the same time it 

 must be recognised that scientific advance has 

 introduced previously unsuspected dangers ; and 

 while it is essential that nations which desire to 

 preserve their independence should study the appli- 

 cation of science to warfare, the terrible weapons 

 which modem discovery places in the hands of un- 

 scrupulous nations, and the devastating nature of 

 modern warfare, cause one to tremble for the future 

 history of mankind if means cannot be found to 

 eliminate the evil. Vital statistics clearly show that, 

 with the present normal rate of growth of populations, 



NO. 2818, VOL. 112] 



the world will, in a comparatively short pericxi. 

 become incapable of supporting its teeming imllions, 

 in spite of the possibilities of increasing the pro- 

 ductivity of the soil. 



The overspill of dense f>opulations provokes situa- 

 tions from which apparently there is no escape, for 

 it involves agreement as to expansion, and the 

 much-discussed question of birth control has to be 

 seriously considered. A review of the whole realm 

 of Nature warns us that there may be no way of 

 escaping the great issue. May it not be then accepted 

 that, as long as human nature is what it is now, war 

 is certain, even if it be not inevitable. The way could 

 come in peace, but only through a world-wide dis- 

 cipline, vastly more thoroughgoing than any discipline 

 we dream of at pre.sent. 



The address concludes with a plea for the creation 

 of a national appreciation of science, for improvement 

 of scientific education, and for the development of 

 research. 



' ' Our hope is to see a new spirit bom here. No 

 one knows what lies on the knees of the gods. But 

 there is something within the mind and heart of 

 any great people which responds to the dream of 

 excellence, and inflames when the vision of national 

 destiny is before it. Our Mother-land has had a 

 great past. Is its offspring here in southern seas, 

 illumined by ' the gem |X)inted cross and the blaz- 

 ing pomp of Orion,' to rise to material, to intel- 

 lectual, and to moral greatness among earth's 

 peoples ? If so, the path is strenuous, but glorious. 

 AU visions of ease and luxury are but opiates, and 

 lead to destruction. We shall need to gird ourselve> 

 for the tcisk, and create for ourselves a world where 

 our sons, knowing something of the splendid mysteries 

 of the boundless universe, and also of our own little 

 world, will excel in the art of using to the full the 

 heritage our nation has given us. Then indeed will 

 science have rendered noble service to the sons of 

 Australasia." 



