16 BASIC ASSUMPTIONS 



the early twentieth century asserted the statement omne vivum 

 ex vivo was, therefore, like most dogmatisms, ill timed." 



The argument developed so far, then, is as follows. The 

 ancients thought that in many cases it was possible for living things 

 to be created de novo. All these cases depended upon poor 

 observation or lack of knowledge, and gradually as information has 

 become available all the higher animals have been shown to arise 

 from previous generations. The simpler forms of life such as 

 yeast and bacteria were at one time thought to arise spontaneously, 

 but controlled experiments showed that these observations were 

 at fault. The conclusion is thus that the onlv cases where we think 



j 



that life may be formed de novo are those where we have no 

 information as to the mode of origin. From this one might suppose 

 that spontaneous generation does not take place, but this is an 

 unjustified extrapolation. The correct extrapolation would be 

 that until we have devised experiments in which the simpler forms 

 of life, such as viruses, are developed de novo, we have no evidence 

 of de novo origin of life. This does not imply that de novo genera- 

 tion is or was impossible: Oparin (1957) suggests that life was 

 created de novo on this world at one time and it is possibly being 

 created now somewhere in the universe, but it is not being 

 created now in this world since the ubiquitous presence of living 

 bacteria would prevent the accumulation of the necessary raw 

 materials for the formation of life de novo. When life was first 

 created there were no such bacteria and hence the necessary 

 substances accumulated. If we accept Oparin's view that life is 

 not formed de novo at present in the world, there are still two 

 alternative suggestions concerning the origin of life. The first is 

 that life is still being formed de novo in other parts of the universe 

 and is then transmitted by meteorites to this planet. Ousdal 

 (1956) has described in meteorites some very interesting shapes 

 which in some ways resemble present-day living forms (Fig. 1). 

 However, the meagre evidence so far available that meteorites may 

 contain living material is not yet convincing. It should be noted 

 that the present climate of opinion concerning the possible 

 mechanism of the evolution of the present solar system is changing. 

 The view suggested by Sir James Jeans that the planets were 

 formed by the unique passage of a giant star near to the sun is 

 no longer strongly supported (Lyttelton 1956). Instead it seems 



