254 



NATURE 



[November 5, 19 14 



part of a flame, must have great influence over the 

 combinations there taking place " (656). The last 

 sentence is interesting in connection with the work of 

 Prof. Bone on surface combustion. 



It is, perhaps, rather to be wondered at, since Fara- 

 day had gone so far in the interpretation of the 

 phenomena, that he did not take the further step and 

 bring them into relation with surface tension, to 

 which Thomas Young had already directed attention. 



In the application of these facts to the theory of 

 enzyme action, the view was first definitely put for- 

 ward b)' myself, so far as I know, in a paper in the 

 Biochemical Journal, vol. i. (1906), pp. 222-27, that 

 the "combination" between an enzyme and its sub- 

 strate is of the nature of an adsorption. This view 

 has received more and more support from work done 

 by various investigators since that time. To mention 

 one fact only, it has been found in the cases of several 

 difi'erent enzymes that their activity is exercised in 

 liquids in which they are completelv insoluble, so that 

 it must be the surface of the particles which is con- 

 cerned. We know also that, in water, enzymes in 

 general are in the colloidal state, a state in which 

 chemical reactions obey laws which interfere with that 

 .of mass action in its simple form. 



It is very doubtful whether intermediate compounds 

 of a chemical nature play any part in catalysis by 

 enzymes. None, at all events, have been shown to 

 exist. Moreover, such an explanation is of very rare 

 applicatiori to catalysis of any kind. The hypothesis 

 of the action of enzymes which is most in agreement 

 with all the facts known at present may be stated 

 somewhat as follows : the molecules which are to 

 enter into reaction are condensed by adsorption on the 

 surface of the colloidal particles of the enzyme and 

 their final state of equilibrium is brought about at a 

 greatly accelerated rate. Whether, as Faraday seems 

 to hold, the close approximation, and high concentra- 

 tion, is in itself sufficient to account, by mass action, 

 for the increased rate of reaction is a matter for future 

 investigation. It may well be, as Hardv points out 

 (Proc. Roy. Soc, vol. Ixxxviii. B, pp. 174 and 175), 

 that it is in the actual process of condensation itself 

 that the molecules are subject to stresses which result 

 in exceptional chemical activity; their chemical poten- 

 tial may very w-ell be raised in the process. It appears 

 to be a phenomenon of very general occurrence' that 

 it is in the very act of change of state that special 

 activities are manifested. This is particularly obvious 

 in living organisms, where a system in equilibrium 

 is dead, but it applies also to non-vital systems. 



I would finally point out that it should not be stated 

 that the action of enzymes does not obey mass action. 

 Mass action is universal in its application ; but, in 

 heterogeneous systems it is controlled by other factors, 

 such as diffusion and surface adsorption, the latter 

 factor playing the chief part in the velocitv of reaction 

 in micro-heterogeneous systems, such as those of 

 colloids. The rate of the reaction is conditioned bv 

 the relative masses of the molecules condensed on the 

 surface at any one moment of time. It wjll be seen 

 that the difficulty of applying the law of mass action 

 consists in the determination of the real active masses. 



W. M. Bavliss. 



Institute of Phvsiologv, Universitv College, 

 Gower Street, W.C. ' 



Tidal Friction and Ice Ages. 



A CAREFUL Study of the conditions of land height 

 during the earlier stages of the Ouaternarv glacial 

 period seems to show that the earth was then less 

 oblate, i.e. the north and south polar regions stood 

 higher than now, to the extent of as much as 10,000 ft. 

 in places, while the equatorial regions stood lower, by 

 NO. 2349, VOL. 94] 



some 500 ft. The spreading of ice-sheets from these 

 high lands may well have been the initial cause of the 

 cooling which produced the Glacial epoch. 



Going further back in geological time, we find, as 

 is well known, a series of long periods of epeiro- 

 genetic movement alternating with long periods of 

 marine transgression. The last great change seems 

 to hav.e been continuous from Carboniferous times, 

 with a girdle of land round the equator high enough 

 to be heavily glaciated, through Mesozoic times, with 

 a marine transgression, to Pliocene times, when the 

 high land emerged at the poles. 



Qualitatively, at least, it seems possible to read the 

 late Sir G. H. Darwin's theory of tidal friction into 

 these changes. By that theory, owing to the differen- 

 tial attraction of the moon on the tidal protuberances, 

 the rotational momentum of the earth is gradually 

 decreasing. This decrease may manifest itself in two 

 ways, either by an actual decrease in the rotational 

 velocity, or by a decrease in oblateness, i.e. by a 

 movement of matter towards the poles. 



It is probable that the earth's crust has a certain 

 tendency to slide on its nucleus, and since the effect 

 of tidal friction is chiefly felt in the crust, while the 

 bulk of the momentum must lie in the heavy nucleus, 

 it follows that the effect of tidal friction must be to 

 tend to slide the crust round the nucleus parallel with 

 the equator. As the crust must vary both in thick- 

 ness and in the closeness with which it is attached 

 to the nucleus, this means a thrust against the deeper 

 and more closely attached portions. The thrust would 

 tend to force some of the crust poleward on either side 

 from the equator, i.e. to decrease the equatorial bulge. 



But the friction between crust and nucleus is very 

 great, and must in time result in an appreciable 

 decrease in the angular velocity of the latter. Prob- 

 ably the action takes place in alternating steps — 

 periods of constant rotational velocity, combined with 

 a gradual thrusting of the crust poleward from the 

 equator, alternating with periods of stability of the 

 crust and gradual decrease in the rotational velocity. 

 The former are periods of earth movement, mountain 

 forming, and disturbance, resulting in the gradual 

 deepening of the ocean over the equator and emerg- 

 ence at the poles ; the latter are associated with a 

 slow retirement of the ocean towards the poles, resulting 

 in marine transgressions in middle and higher lati- 

 tudes. 



I have been able to accumulate a great deal of 

 evidence which supports the theory I have outlined 

 above on the geological side. I am, however, not 

 sufficiently a mathematician to be able to satisfy 

 myself that the cause, tidal friction, is commensurable 

 with the effects, and I am begging the publicity of 

 your columns to ask if someone better situated will 

 help me in that respect. C. E. P. Brooks. 



" Homeleigh," 3 Roseleigh Avenue, 



Highbury, N., October 10. 



At the Editor's request I contribute a few remarks 

 on Mr. Brooks's letter. The suggestion that tidal 

 friction might be a cause of changes in the distribu- 

 tion of land and water is not new. It will be found 

 in a "Note" in Nature of April 25, i88q (vol. xxxix., 

 p. 613), where it is attributed to M. A. Blytt ; and 

 that may not be its first appearance. The character 

 of the changes is that indicated by Mr. Brooks, but 

 the mechanism by which they are effected is a little 

 different. The hypothesis of a crust riding more or 

 less freely on a nucleus is unnecessary, and difficult 

 to reconcile with well-established results. Again, the 

 frictional stresses do not operate directly to cause a 

 flow of material towards or away from the poles, but 

 indirectly by diminishing the speed of rotation. 



The mechanical process may be followed very easily 



J 



