458 



SCIENCE 



[N. b. Vol. XXXII. No. 823 



farther than this and ventux'e to say that 

 the energy evolved in muscular contrac- 

 tion, that also involved in secretion and 

 excretion, the force concerned in the phe- 

 nomena of nuclear and cell division, and 

 that force also engaged by the nerve cell in 

 the production of a nerve impulse are but 

 manifestations of surface tension. On this 

 view the living cell is but a machine, an 

 engine, for transforming potential into 

 kinetic and other forms of energy, through 

 or by changes in its surface energy. 



To present an ample defence of all the 

 parts of the thesis just advanced is more 

 than I propose to do in this address. That 

 would take more time than is customarily 

 allowed on such an occasion, and I have, in 

 consequence, decided to confine my obser- 

 vations to outlines of the points as specified. 



It is not a new view that surface tension 

 is the source of the muscular contraction. 

 As already stated, the first to apply the 

 explanation of this force as a factor in cel- 

 lular movement was Bngelmann in 1869, 

 who advanced the view that those changes 

 in shape in cells which are classed as con- 

 tractile are all due to that force which is 

 concerned in the rounding of a drop of 

 fluid. The same view was expressed by 

 Rindfleisch in 1880, and by Berthold in 

 1886, who explained the protoplasmic 

 streaming in cells as arising in local 

 changes of surface tension between the 

 fluid plasma and the cell sap, but he held 

 that the movement and streaming of 

 Amo&hcB and Plasmodice are not to be re- 

 ferred to the same causes as operate in the 

 protoplasmic streaming in plant cells. 

 Quincke in 1888 applied the principle of 

 surface tension in explaining all proto- 

 plasmic movement. In his view the force 

 operates, as in the distribution of a drop 

 of oil on water, in spreading protoplasm, 

 which contains oils and soaps, over sur- 

 faces in which the tension is greater, and as 



soap is constantly being formed, the layer 

 containing it, having a low tension on the 

 surface in contact with water, will as con- 

 stantly keep moving, and as a result pull 

 the protoplasm with it. The movement of 

 the latter thus generated will be continu- 

 ous and constitute protoplasmic streaming. 

 In a similar way Biitschli explains the 

 movement of a drop of soap emulsion, the 

 layer of soap at a point on the surface of 

 the spherule dissolving in the water and 

 causing there a low tension and a stream- 

 ing of the water from that point over the 

 surface of the drop. This produces a cor- 

 responding movement in the drop at its 

 periphery and a return central or axial 

 stream directed to the point on the surface 

 where the solution of the soap occurred 

 and where now a protrusion of the mass 

 takes place resembling a pseudopodium. 

 In this manner, Biitschli holds, the con- 

 tractile movements of Amaebce are brought 

 about. In these the chylema or fluid of the 

 foam-like structure in the protoplasm is 

 alkaline, it contains fatty acids and, in con- 

 sequence, soaps are present which, through 

 rupture of the superflcial vesicles of the 

 foam-like structure at a point, are dis- 

 charged on the free surface and produce 

 there the diminution of surface tension 

 that calls forth currents, internal and ex- 

 ternal, like those which occur in the case 

 of the drop of oil emulsion. 



A. B. Macallum 

 (To be continued) 



METEOROLOGY AT TBE SHEFFIELD MEET- 

 ING OF THE BRITISH ASSOCIATION 

 The work on meteorology for the British 

 Association for the Advancement of Science 

 is organized under Section A — Mathematical 

 and Physical Science — and under the subsec- 

 tion (6) Cosmical Physics and Astronomy. 

 There can be no more pronounced recognition 

 of the opinion that meteorology has already 

 made good its claim to be considered as a sub- 

 ordinate branch of solar and cosmical physics, 



