VI] THE GIBBS-THOMSON LAW 281 



of motion, sometimes in the mere invisible transfer of molecules 

 but often in the production of visible currents of fluid or manifest 

 alterations in the form or outUne of the system. 



The physiologist, as we have already remarked, takes account 

 of the general phenomenon of adsorption in many ways : particu- 

 larly in connection with various results and consequences of 

 osmosis, inasmuch as this process is dependent on the presence 

 of a membrane, or membranes, such as the phenomenon of adsorp- 

 tion brings into existence. For instance it plays a leading part 

 in all modern theories of muscular contraction, in which phenome- 

 non a connection with surface tension was first indicated by 

 E'itzGerald and d'Arsonval nearly forty years ago*. And, as 

 W. Ostwald was the first to shew, it gives us an entirely new 

 conception of the relation of gases (that is to say, of oxygen and 

 carbon dioxide) to the red corpuscles of the blood f. 



But restricting ourselves, as much as may be, to our morpho- 

 logical aspect of the case, there are several ways in which adsorption 

 begins at once to throw light upon our subject. 



In the first place, our prehminary account, such as it is, is 

 already tantamount to a description of the process of develop- 

 ment of a cell-membrane, or cell- wall. The so-called "secretion" 

 of this cell-wall is nothing more than a sort of exudation, or 

 striving towards the surface, of certain constituent molecules or 

 particles within the cell ; and the Gibbs-Thomson law formulates, 

 in part at least, the conditions under which they do so. The 

 adsorbed material may range from the almost unrecognisable 

 pelUcle of a blood-corpuscle to the distinctly differentiated 

 ''ectosarc" of a protozoan, and again to the development of a 

 fully formed cell-wall, as in the cellulose partitions of a vegetable 

 tissue. In such cases, the dissolved and adsorbable material has 

 not only the property of lowering the surface tension, and hence 



* G. F. FitzGerald, On the Theory of Muscular Contraction, Brit. Ass. RejJ. 

 1878; also in Scientific Writings, ed. Larmor, 1902, pp. 34. 75. A. d'Arsonval, 

 Relations entre I'electricite animale et la tension superficielle, C. B. cvi, p. 1740, 

 1888; cf. A Imbert, Le mecanisme de la contraction musculaire, deduit de la con- 

 sideration des forces de tension superficielle, Arch, de Pliys. (5), ix, pp. 289-301 , 1897. 



t Ueber die Natur der Bindung der G^se im Blut und in seinen Bestandtheilen, 

 Kolloid. Zeitschr. ii, pp. 264-272, 294-301, 1908; cf. Loewy, Dissociationsspan- 

 nung des Oxy haemoglobin ini Blut, Arch. f. Anat. und Physiol. 1904, p. 231. 



