DISTRIBUTION OF ORGANIC SUBSTANCES 121 



of meteorites from this point of view. In his book Geo- 

 chemistry A. Fersman^" gives an extensive review of these 

 investigations. He indicates the tremendous significance of 

 the study of meteorites in the solution of geochemical prob- 

 lems. He writes: 



It may be that we are only now beginning to understand what 

 a very important part a thorough and well worked out analysis 

 of meteorites can play, both in determining the composition of 

 the Earth, and in clarifying the laws governing the difference 

 between the composition of the crust of the Earth and the 

 composition of the Earth as a whole. This is essential to a clear 

 understanding of the quantitative occurrence of the elements 

 in the parts of the crust of the Earth accessible to us. 



A. Fersman presented a whole series of comparative analy- 

 ses of meteorites and of various terrestrial formations. These 

 figures revealed striking correspondence between the over-all 

 composition by weight of the Earth and the average composi- 

 tion of meteorites, a correspondence which cannot be acci- 

 dental. All this led him to the conclusion 



that both in respect of the nature of their elements and in the 

 principle on which their atoms are built, the elements found in 

 meteorites are very similar to those found in the deepest zones 

 of the crust of the Earth, and that, in all probability, they 

 correspond even more closely to the central parts of the Earth. 



These data have now been considerably amplified by the 

 inclusion of new analyses and the consideration of a number 

 of new circumstances (e.g. H. Brown and C. Patterson, ^^ 

 H. C. Urey and H. Craig,'- and P. Chirvinskii'^). The basic 

 conclusions reached by Fersman remain, however, un- 

 changed. The reason for this close correspondence between 

 the chemical composition of the meteorites and that of the 

 Earth is certainly that both the Earth and the meteorites 

 developed from one and the same original material. Never- 

 theless, different authors have held different views on the 

 way in which meteorites were formed. 



Most astronomers and geologists consider that meteorites 

 arose in the solar system by the disintegration of a ' mother ' 

 planet, similar in composition to the Earth, but considerably 



