Descent oe Man. 239 



attention to the connection subsisting between an 

 animal and its environments, especially in the lower 

 organisms, as he found therein a cause of the differ- 

 entiation of similar species and development of new 

 species entirely dissociated from Darwin's doctrine 

 of " natural selection." Perceiving, for instance, how 

 the homogeneous protoplasm of a ruptured vaucheria 

 escaping into water envelops itself, simply through 

 the chemical action of its environments, with a firm 

 peripheral covering (a covering out of which, as we 

 have seen, higher animals than gastrula primarily 

 evolve all the organs of sense and the nervous 

 system), he suggests that the inevitable contact of a 

 lowly organism's epiblast and hypoblast with its 

 surroundings, whether touched or tasted, virtually 

 originates those rudimentary formations which gradu- 

 ally develop into the immense variety of animal 

 motors and sense-organs. Hence, by a difference 

 in the nature, temperature, transparency, motion, 

 etc., of its environments, a gastrula, or even a 

 young foetus in the womb may develop new 

 organic variations which virtually entitle it, when 

 fully developed, to be called a new species of its 

 own genus. 



Not only so, but what is doubly important from 

 the mental side of the problem, the nature of an 

 animal's intelligence, dependent as this intelligence 

 wholly is on an animal's sense-organs and nervous 

 system, must also be largely influenced in its evolu- 

 tion from a lower grade of intelligence by the kind of 



