188 GENERAL DISCUSSION [ch. xiv 



backed by the universal occurrence of the hollow curves, shows 

 that there is a general law, probably electrical, at the back of it. 

 And if evolution goes on without reference to adaptation values, 

 each genus giving rise to another, and both surviving (as a rule), 

 then the hollow curve becomes an integral part of it. Further 

 refinements must be left to the mathematicians, and will doubt- 

 less provide interesting results. 



Differentiation is not based upon adaptation at all, the 

 latter remaining a primarily physiological phenomenon. The 

 ordinary type of adaptation, that is familiar to agriculturists, 

 is described in the following extract from a paper by Cockerell. 

 " In California certain scale insects, subjected to poisonous fumes 

 by the horticulturists, have, by a process of the survival of the 

 fittest, developed resistant races, not distinguishable by any 

 morphological characters." The writer was very troubled by 

 cockroaches in his (tropical) house, and used a certain much- 

 advertised poison, but though at first the death-rate was very 

 high, presently there appeared a race of cockroaches that was 

 immune, but looked exactly the same as their predecessors. "The 

 chance of introducing from outside an all-round superior strain 

 diminishes as the adaptation of the local strain to its environ- 

 ment increases" (77, p. 283). Many similar extracts from agri- 

 cultural papers might be quoted. 



There is good reason to suppose that in some way the genes 

 and chromosomes are immediately responsible for the evolution 

 that is going on. Their divisions and fusions strongly suggest some 

 electrical process, with which the suggested action of cosmic rays 

 may have something to do. Or again, something of the nature of 

 genie changes may be going on, and occasionally result in the 

 taking up of "more or less stable positions of equilibrium in cell 

 division" as suggested by the writer in 1907. The apparently 

 purposeless way in which distinguishing characters go together is 

 verv like the similar behaviour seen in anv mutation involving 

 more than one character. There is no evident reason, nor sugges- 

 tion of reason, why a Monocotyledon should have at the same 

 time one cotyledon, a trimerous flower, a parallel-veined leaf, and 

 a peculiar anatomy. Nor why Cruciferae should have tetra- 

 d}aiamous stamens, Dryas eight petals, and so on. Nothing but 

 the direct effect of the genie composition, with heredity, will 

 explain why the characters are shown in perfection. 



The continual appearance of characters with complex correla- 

 tion that could not be due to selection, such as the characters of a 



