No. 606] 



BIOLOCICAL ENIGMAS 



337 



to that of the ma-;s of >inall crystals, compacted together, 

 which always results from the rapid crystallization of a 

 supersaturated solution of a siil)viiui(H' like. v. n., -odium 

 thiosulphate. 



It is evident, then, that the -i'lirr.-il iIu-oin of ciMlx-i^ 



which almost certainly depends ui)on the de])osition, or 

 adsorption of the ]-eactin,ii- ^ulxtances upon the surfaces 

 of colloidal particles. -^ Such adsorption, the molecular 

 mechanism of which has been made very clear by Lang- 

 muir,-^- will tend to be spcH'ilic, and the more specific tlie 

 more complex is the structure of the units making up the 

 mosaic of tlie surface. Molecules the lield patterns of 

 which fit closely into the fields of the Mirface will tend to 

 displace others having a cruder corre-pondeiUH'. This 

 follows from either electro-dynamics or tliermodMinniic^, 

 and obviously coincides with Fischer's ('las>ical coiice]")- 

 tion of the lock aiid key relation between eii/ynie and snl)- 

 strate.''-' 



It will he i)erceiv(Ml that our theors tin- rMt.-ihtic 

 process i> -inipls a n ruKMiicnl and i-- 

 sical theory of intcrnKMlialc cottih- ,i- 

 been proven ti-iio in so iii;in\ in-lan.- ■ .11 

 compounds." whidi i>l;i\' \\\v prinnj-a; r-:. n, ^.i'.-.iiic 

 action, do iioi <\\\'U^y (hiianiically iVoiii i-iiciuical com- 

 pounds in u.Mifi.-iK -jjKf PC t'liKM- .-an-inu ad-orption 



Conversely, catalxtic adion iii wliicii tiie calaly^t is in a 

 molecular or uni)olyniiM'Iz( d state will not necessarily 

 differ in its meclianistii from tliat cliaracleristic of en- 

 zymes or of metallic snrl'aco. 



IV 



The suggestion that t/c t iindanictital lit'c pro.M-^ of 



