lOO A SCIENTIFIC APPROACH 



which are now appearing in the world literature in greater 

 and greater numbers. It is not only biologists who take part 

 in these investigations but also physicists, astronomers, geolo- 

 gists and chemists having different specialised interests. 



In this chapter we can only enumerate briefly a few of 

 these researches and reviews. They are discussed in more 

 detail in the appropriate places in later chapters. 



First we must mention the work of H. C. Urey.^® Starting 

 from an analysis of the thermodynamic and kinetic laws and 

 the geophysical and geochemical results which can be deduced 

 from them, he drew a picture of the primary formation of 

 organic substances in the course of the development of the 

 Earth, and of their further evolution in the first period of its 

 existence. These studies served as a basis for the very valuable 

 experimental work of S. L. Miller" who synthesised amino 

 acids from those gases which may be presumed to have been 

 present in the original atmosphere of the Earth. 



In his well-known book The physical basis of life/^ and in 

 a number of later papers^^ and pronouncements,^" J. D. 

 Bernal approached the problem of the origin of life from a 

 physical and physico-chemical standpoint. He cast light on 

 many of the stages of the evolution of organic-chemical 

 substances and put forward very interesting ideas about the 

 first development of asymmetry in organic substances and the 

 possibility of their being adsorbed on particles of clay in 

 primaeval pools. In a recently published article V. M. 

 Goldschmidt" threw light on the geological aspects of the 

 problem. 



A great deal of work has been done towards explaining the 

 general evolution of matter leading up to the development of 

 living things. According to their own specialities the authors 

 concentrated on the explanation of one or another stage of 

 this historical process. We may mention here the numerous 

 papers by N. W. Pirie,^^ J. B. S. Haldane,^^ R. Lemberg,^^ 

 and the reviews of U. N. Lanham," G. Wald,^« S. Kirkwood," 

 F. Cedrangolo^^ and many others. In his experimental work 

 J. J. Scott" pays great attention to the possible way in which 

 porphyrins might have developed. A. Gulick'" and L. Roka'^ 

 consider the formation of high-energy phosphorus compounds 

 and polynucleotides ; while G. Ehrensvard" and S. Akabori'^ 



