EVOLUTION 



919 



For in spite of their great diversity of shape and use, they are 

 strictly homologous. There are many structural differences, a loss 

 of this and an exaggeration of that, but the large fact is the recur- 

 rence of the same fundamental bones, muscles, blood-vessels, and 

 nerves. Everything is new, and yet everything is old; the same 

 material is fashioned into varied guise. There is no possible interpre- 

 tation of this except the evolutionist one, that we are dealing with 

 a genetic series of blood-relations. 



Similarly, what other interpretation can be put upon the frequent 

 occurrence of vestigial structures (separately discussed), or on 



Fig. 157. 



Another Mode of Branching of a Genealogical Tree. After De Vries. At 

 different levels of the main stem, from successive plastic stocks, there 

 has been an abundant whorl-like radiation of species in many directions. 

 The two long lateral twigs show how types originating at a lower level 

 may surpass in their individuation the types on the next higher level or 

 whorl. 



"Nature's way" of making a very new thing out of something very 

 old? We must guard against the fallacy of supposing that one species 

 or even organ is transformed into another; what has happened has 

 been the emergence and divergence of one species from another by 

 means of new departures or mutations, and the origin of one organ 

 out of another which evolved something novel out of the old. The 

 elephant's trimk was a striking novelty, which took a long time to 

 reach its modem perfection; yet what is it but an elongated nose, 

 plus a piece of upper lip ? Such intricate novelties as the sting of a 

 bee and the spinnerets of a spider must be traced back to a 

 commonplace origin as abdominal limbs. 



Not to be forgotten is the possibility of drawing at least the 

 outline of a genealogical tree, of linking class to class by means of 



