Claus et al.: "Organized Elements" in Chondrites 581 



terrestrial biological processes includes the finding of what seems to be biochemi- 

 cal compounds in carbonaceous meteorites. Nagy et al. (1961a), and Mein- 

 schein et al. (1963), reported isolation of complex, saturated, and aromatic 

 hydrocarbons, respectively. Anders (1962) and Krejci-Graf (1962) criticized 

 these findings and the interpretations. However, a rebuttal has been offered 

 (Nagy et al., 1962). Calvin (1961) and Briggs (1961) reported the finding of 

 compounds which might be cytosine or purines, respectively. It should be 

 noted that bituminous organic matter was isolated from the Orgueil meteorite 

 by Cloez (1864), only a few weeks after the meteorite fell. This fact suggests 

 that a sizeable portion of the meteoritic organic matter is likely to be of extra- 

 terrestrial origin. 



Mineralogical and petrographical studies have shown that the parent body 

 (ies) of carbonaceous chondrites was capable of supporting a form of life. It 

 seems that liquid water was present and that this low-to-moderate temperature, 

 aqueous environment was slightly alkaline and somewhat reducing. Extrap- 

 olation of the parent body environment from the known mineral assemblage 

 in terms of phase equilibria data in />H-redox systems has been published by 

 Nagy et al. (19616), and in more detail (1963). Similar conclusions, arrived 

 at by independent studies, have been advanced by DuFresne and Anders (1962). 

 Petrographical observations by Nagy and Claus (1963) showed that the meteor- 

 ite parent body had been subjected at one time to mechanical stresses that 

 produced fractures which were later filled with magnesium sulfate. The 

 textural patterns of the Orgueil and Ivuna carbonaceous chondrites resemble 

 certain terrestrial rocks, such as pyroclastic rocks, deposited in water from 

 fragmental volcanic debris. They also resemble silicate rocks altered by 

 hydrothermal solutions. These petrographical studies have also shown that 

 the interior of the meteorites does not contain evidence for high temperature 

 effects acquired during the fall through the Earth's atmosphere. Conse- 

 quently, organic microstructures and unorganized biochemical type compounds 

 could have arrived in the meteorites without destruction by heat. The study 

 of petrographical thin sections also suggests that the average pore size of the 

 Orgueil and Ivuna meteorites is too small (<1 n) to permit the entrance of 

 most airborne terrestrial contaminants. 



The micropaleontological examinations, the biochemical analyses, and the 

 mineralogical and petrographical measurements strongly suggest that biologi- 

 cal activity was active at one time on the meteorite parent body. A full 

 evaluation of the origin of the organized elements must involve a consideration 

 of fine morphological structures, the applicability of biological stainings and 

 other microchemical methods. 



Two suggestions had been advanced to explain the origin of the organized 

 elements, provided that they will prove to be indigenous microfossils in the 

 carbonaceous chondrites. Bernal (1962) suggested that life may have evolved 

 along similar lines at various places in the Universe. Urey (19626) suggested 

 that the organized elements are terrestrial forms that contaminated the moon 

 from Earth during early geological times. According to Urey's concept, bio- 

 logical matter and water may have been transferred to the moon, which was 

 at that time closer to earth, by the impact of meteorites into terrestrial bodies 

 of water. The carbonaceous meteorites are thought to come from the moon. 



