Meinschein et al. : Evidence in Meteorites of Former Life 575 



quickl}^ and, in the thin molten surface layers of the falling meteorites, tem- 

 peratures far in excess of 180° C. were reached. Even from these thin melts, 

 sizeable volumes of gases may have been expelled. During their plummet to 

 Earth, carbonaceous chondrites probably lost more volatile carbonaceous 

 substances then they received from the atmosphere. 



When the meteorites struck Earth, their hot surfaces may have distilled or 

 decomposed organic matter, and cool portions of the chondrites may have 

 condensed and collected the vapors. But, the burned crusts of recovered 

 fragments of carbonaceous chondrites cover only a fraction of the stones. 

 These crusts are very thin, and the fragments are friable. It is doubtful that 

 the heat or impact energies of these stones could have vaporized more than a 

 trace of terrestrial organic matter. If carbonaceous chondrites are con- 

 taminated appreciably, they probably acquired most of the contaminants 

 after the fragments were collected. 



Analyses of the Holbrook chondrite show that this stone was not greatly 

 contaminated either during its fall or almost 50 years of storage on Earth. 

 Nevertheless, the carbonaceous matter in the Murray and Orgueil meteorites 

 may have been defiled. Carbonaceous chondrites are more porous than 

 ordinary chondrites, and the Murray and Orgueil contain higher concentrations 

 of carbon than the Holbrook. Organic materials may be strongly adsorbed 

 on carbonaceous substances. Thus, the Murray and Orgueil fragments were 

 probably more susceptible to contamination than the Holbrook. Notwith- 

 standing, the high concentrations of benzene extractable materials in the 

 Murray and Orgueil cannot be easily explained by natural contaminants. 

 Why in 10 years should the Murray, or in 100 years should the Orgueil stones 

 accumulate much more extractable carbonaceous substances than an average 

 soil collects in thousands of years? It seems likely that most of the carbon 

 compounds in the Murray and Orgueil fragments were either indigenously 

 formed in the parent body or carelessly added by man. 



Meteorites are handled, and some are marked for identification. Oily 

 hands, paints, wax pencils, polishes on display cases, plasticizers in plastic 

 storage cases, microorganisms, pyrolysis products of fossil fuels in urban 

 atmospheres, lacquer coatings, and other carbonaceous substances may have 

 contacted and contaminated the Murray and Orgueil fragments. Contamina- 

 tion has been considered a major problem throughout this investigation, and 

 appreciable attention has been paid to this problem. 



Fragments of the Orgueil meteorite were obtained from two museums and 

 the Murray fragments came from another collection. Contaminants from 

 these various locations should have been quite different, but none of the 

 variations in the compositions of the meteoritic extracts suggested significant 

 organic contamination. All of the fragments were carefully inspected and no 

 evidence of markings or coatings were observed. Microscopical examina- 

 tions'^"^ show that recent terrestrial type organisms are present in the Murray^'' 

 and Orgueil in numbers that are two or more orders of magnitude less than in 

 the average terrestrial sediment. Microorganisms usually contain from 1 to 3 

 parts per thousand by weight of hydrocarbons. These concentrations are only 

 slightly greater than those of the hydrocarbons in the Orgueil (table 2). 

 Terrestrial organisms which have existed in the meteorites, seem to have been 



