EARLY HISTORY OF LIFE 



31 





Fig. 2-8. Pictures of viruses taken through an electron 

 microscope. A. Tobacco-mosaic virus (X60,000). B. 

 Bushy stunt virus from tomato plants (X85,000). Note 

 the regular arrangement of the particles. C. Virus that 

 attacks bacteria (bacteriophage) are the tiny club- 

 shaped particles. The large white spheres are used 

 as a means of measuring the size of the virus particles. 



our atmosphere they burn to incandescence. 

 Life, as we know it, certainly could not 

 withstand such high temperatures. It seems 

 more within the realm of probability that 

 life originated on this planet a long time 

 ago. Geologists tell us that there was a time 

 about 1 billion years ago when conditions 

 were such that life could have started. 

 Those conditions do not exist today, so it is 

 unlikely that life is being generated now. 

 Assuming this to be true, what are the most 

 logical steps that could have taken place in 

 its inception? From this point on, let us 

 follow the speculations of Haldane ( a Brit- 



ish scientist) and Oparin (a Russian sci- 

 entist), two men who have formulated a 

 theory of the origin of life on earth. A 

 sketch such as that shown in Fig. 2-7 might 

 also be helpful. As plausible as this theory 

 may seem, it is far from proven, and it is 

 improbable that satisfactory proof will ever 

 be forthcoming. 



All living things are composed of com- 

 plex substances called organic compounds. 

 They contain carbon atoms as the central 

 core around which hydrogen and oxygen 

 have accumulated in a precise manner 

 to form such substances as ethvl alco- 



