CH. XXI] AND THE MUTATION THEORY 225 



which external conditions those types have originated, all specu- 

 lations concerning their evolution on the ground of their uses 

 must be considered to be more of a poetical than of a really 

 scientific nature. Wherever striking adaptations to the environ- 

 ment are met with, we will always have to grant that they did 

 not originate under the conditions of the locality, where we 

 observe them, but elsewhere and in long forgotten times, the 

 environmental conditions of which are necessarily imknown to us. 

 Hitherto systematic enquiry Avas obviously handicapped by 

 the weight of such objections, and they were simply left out of 

 consideration. No principle was known, which would enable us 

 to decide the question, Avhether advantageousness to their 

 bearers had played any role in the evolution of new characters. 

 Later on, after many wanderings of a species into different new 

 environments, a character might prove to be useful in some of 

 the new localities, and here induce a rapid multiplication. 

 Striking adaptations, such as those of desert plants, may be 

 the consequence. But whether the characters have evolved 

 under analogous or under quite different conditions, we do not 

 know. 



It is at this point that the theory of Age and Area has come 

 into the discussion. It showed that the dispersal of species, 

 especially in the first period after their birth, is independent of 

 their distinctive morphological characters. This phenomenon 

 may be studied on a purely statistical basis without the aid of 

 personal appreciations of biological qualities. 



In the first place, the discovery tJiat endemic species are, as 

 a rule, the youngest in their country, has provided us with a 

 means of judging the value of their characters in the struggle 

 for life. But even here such a relation is not observed. The en- 

 demic forms of Coleus of Ceylon, and numerous other instances, 

 show their marks to be minute and of subordinate importance, 

 although they are recognised by the best systematists as having 

 full specific value. Many endemic species are still living in the 

 same locahty and obviously under at least almost the same con- 

 ditions as those under Mhich they have originated. But no 

 relation of their new marks to any use in the struggle for exist- 

 ence can be pointed out. They have inherited their adaptation to 

 the environment from their ancestors, but are rarely known to 

 have increased it. Only in some cases they have succeeded in 

 spreading rapidly and widely, and then, of course, an improxe- 

 ment in adaptation may be granted. But even here there is 



