CHAPTER XII 



THE EVOLUTION OF PLANTS (Continued) 



The oft-expressed view that the ocean has been the great 

 center and originator of Hving bodies is ahnost wholly nega- 

 tived when a study of the bacteria and fungi in general is 

 made. For, since practically all of these depend on organic 

 food for sustenance, it might be supposed that many marine 

 plants and animals would habitually be associated Tvith def- 

 inite bacterial or fungoid plants. But, comparatively speak- 

 ing, they are almost wholly absent from the sea. For, while 

 at the present day 31 genera and about 600 species of bacteria 

 live in fresh or brackish water, or saprophytically and para- 

 sitically on land plants and animals, only four genera and 

 about 50 species are marine. 



Again, while 2670 genera and about 24,000 species of fungi 

 are distributed over land or swamp areas, the estimate is gen- 

 erous which would place the marine ones at ten genera and 

 about 200 species. The recent recording and description of 

 two new marine species from California indicates that a few 

 may from time to time be added, but the number undoubtedly 

 will always be small. 



There seems therefore absolutely no reason for supposing 

 that either the bacteria or fungi originated other than over 

 land-locked areas. An attempt may therefore be now made 

 to account for their primitive origin, in terms of what we can 

 ascertain as to their life-history. 



We have already postulated the origin of the cyanophyceous 

 algae amid warm thermal springs of mid-archaean age, and at 

 a temperature in some cases of 60-75" C. since living repre- 

 sentatives still show such ancestral capacity. But in many — 

 probably it will be demonstrated in all — thermal waters of 

 60-80° C. a variety of bacteria exist and multiply, the opti- 



325 



