Evolution of Enzymes 131 



magnetic, bivalent cation such as zinc, then this molecule can have a long-lived 

 triplet state, which is essential for the energy-migration and conversion with any 

 high degree of efficiency. 



I suspect that the rudimentary beginnings of a chlorophyll-type of photo- 

 synthesis may have occurred in the precellular period, in a period in which one 

 had already seen the appearance of Hpid-type coacervates and in which the disc- 

 Uke molecules of chlorophyll could assume a pseudo-crystaUine arrangement, 

 facihtating the energy transport and conversion. In all probabihty, it was at 

 this point, or very near this point, that the cellular habit of Ufe took shape. 

 Finally, the generation of the oxygen-evolving mechanism, perhaps requiring 

 the participation of the carotenoids and other such materials, occurred, leading 

 to the liigher plants, and to the whole potential of oxidative evolution. 



