SYMBIOSIS 71 



domestic problems apparently trivial by comparison, and this 

 on the sociological side will be found to throw not a little light 

 on the subject of the greatness of nations. We see that by 

 proper symbiotic effort even the most humble organisms can 

 produce a hereditary bio-chemical mechanism comparable in 

 efficacy to the corpus luteum of the mammalia. It is not even 

 necessary that they belong to the same species. Nay, what is 

 more, we see that the true and complete hereditary mechanism 

 rests normally everywhere upon a dual, i.e., symbiogenetic basis. 

 These lowly types, moreover, in virtue of the adequacy of 

 their symbiotic labours, become veritable pioneers of organic 

 civilisation. In Nature (24/7/13, p. 541) we have a report of 

 Dr. Otto Yernon Darbishire on Antarctic Lichens, and he tells 

 us that : 



In Alpine and Arctic regions lichens do important pioneer work, 

 helping to break up the hardest rock surfaces and prepare soil on which 

 other plants can grow; while on steeply-inclined and bare rock, lichens, 

 along with minute algae, are in general the first colonists. (Italics mine.) 



The lichens are characterised by their excessively slow growth and 

 their great length of life. This slowness of growth is associated with 

 great length of life and it is probable that individuals found grow- 

 ing on hard mountain rocks or on the trunks of aged trees are many 

 hundreds of years old. It is possible that specimens of such long-lived 

 species of Lecidea geographica actually outrival in longevity the oldest 

 trees. 



Truly " Ohne Hast and ohne Rast" seems to be the motto 

 of the lichens. In the production of services and of biological 

 values, in longevity and slowness of growth they compare 

 favourably with many of the highest organisms. They present 

 the symptoms of wholesomeness in many directions at the same 

 time. 



If evolution were merely a matter of achieving reproduc- 

 tion as many biologists seem to believe there would be little 

 need for slow growth, nor for longevity and the expenditure 

 entailed by the retardation of the period of reproduction. But 

 if it is mainly a matter of the maturation of biological values, 

 the raison d'etre of slow growth with associated laboriousness 

 at once becomes clear. 



