260 ORIGIN OF STRUCTURES AND FUNCTIONS 



must proceed at different rates and this must also affect their 

 arrangement. The speed of the reaction whereby amino acid 

 residues are incorporated does not, however, depend entirely 

 on their inherent chemical properties but, in living organ- 

 isms, it is mainly determined by the presence of a collection 

 of enzymes. It follows that the extremely uneven but strictly 

 determined sequences of amino acid residues in the poly- 

 peptide chains, which are to be found in any proteins which 

 have been isolated from living bodies, arise as a result of 

 a pre-existing organisation of their protoplasm. This applies 

 even more forcibly to the three-dimensional structure of 

 corpuscular proteins, which clearly requires for its develop- 

 ment a certain spatial organisation. In the absence of such 

 an organisation which had already been elaborated, there 

 could clearly never have arisen simply in an aqueous solution 

 of organic substances such structures as those of present-day 

 proteins with their peculiar properties. 



This is also evident because the particles of present-day 

 proteins are not only extremely complicated in structure but 

 are also extremely well adapted to carrying out particular 

 biologically important functions. Enzymes, hormones, etc., 

 seem to be perfectly rationally constructed organs of living 

 protoplasm. Therefore the hypothesis that they arose primar- 

 ily in some way, and that protoplasm itself was later gradually 

 built up from them, reminds one of the hypothesis of the 

 ancient Greek philosopher Empedocles, concerning the origin 

 of living things. 



Empedocles believed that at first there arose separate, 

 independent organs: "Out of it (Earth) many foreheads 

 without necks sprang forth, and arms wandered unattached, 

 bereft of shoulders, and eyes strayed about alone, needing 

 brows.""* Later on these disunited members joined them- 

 selves together and in this way there arose various animals 

 and people. 



From the present-day Darwinian point of view the falsity 

 and absurdity of hypotheses of this sort are obvious. Any 

 particular organ can arise and become perfected only by the 

 evolutionary development of the organism as a single whole. 

 The definite, complicated structures of eyes and hands are 

 only adapted to the purpose of fulfilling those functions 



