xvin PAST HISTORY 351 



6. Great Steps in Evolution. It was only after many 

 millions of years had passed that the earth became cool 

 enough to be a home of life, and the origin of living 

 organisms upon it remains shrouded in mystery. It may 

 be that germs came from elsewhere, as Richter, Helm- 

 holtz, and Lord Kelvin suggested, but it is difficult to 

 think of protoplasm surviving transport through space 

 even in the heart of a meteorite. In any case, if the 

 suggestion be true, the problem of origin is simply shifted, 

 not solved. The probabilities are stronger in favour of 

 the suggestion that living organisms of a simple sort 

 evolved somewhere on earth from not-living matter ; 

 in other words, that spontaneous generation occurred. 

 Pfliiger and Verworn have upheld the view that the 

 cyanogen radical (CN) may have been the starting-point 

 of the proteid molecule which is an essential constituent 

 of all living matter. The idea that the living may have 

 evolved from the not -living is in harmony with evolu- 

 tionist thinking, but it is a very difficult hypothesis. The 

 synthetic chemist is able to build up artificially a large 

 number of complex substances, such as sugar, indigo, 

 and salicylic acid, but he has not yet (1916) made prc- 

 teids ; we cannot suggest with much concreteness how there 

 could be effected in nature's laboratory syntheses like 

 those which man's directive reason achieves ; and even 

 the simplest organisms have qualities which we cannot 

 explain in terms of any known properties of inorganic 

 substance. On the other hand, unless organisms arose 

 from the inorganic, their origin remains quite mysterious. 

 But " if the dust of the earth did naturally give rise to 

 living creatures, if they are in a real sense born of her 

 and the sunshine, then the whole world becomes more 

 continuous and vital, and all the inorganic groaning and 

 travailing becomes more intelligible. 1 



First Organisms. We have no means of knowing what 

 the first organisms were like, but it is probable that they 

 were extremely minute like the nuclei of some of the 

 Protists. The late Professor Minchin was strongly of 

 opinion that the earliest living beings were minute, possibly 

 1 Evolution, Geddes and Thomson, p. 72. 



