Influence of Environment iqion the Orrjanism. 459 



the like. The most satisfactory rationale of a set of environ- 

 mental influences known to me is that given by Geddes in 

 his papers on sex (83, 84), where he shows that the conditions 

 favouring the production of male offspring are generally 

 katabolic, and those favouring the production of females 

 are similarly anabolic. This result, reached by adding up 

 the observations of numerous investigators, is in beautiful 

 harmony with the conclusion which he has reached along 

 other lines — that the male is a relatively katabolic, and the 

 female a relatively anabolic, organism. 



8. Susceptibility to Environmental Influence. — In estimating 

 the probable historic influence of the environment, it must 

 be allowed that organisms are variably susceptible to external 

 influence, and that some factors are much more potent than 

 others. The chemical character of the medium, nutrition, 

 heat, and light are evidently more influential external condi- 

 tions of variation than pressure, electricity, or animate 

 surroundings. It is equally obvious that simple and young 

 forms are more in the grip of external surroundings than are 

 complex and adult organisms, so that "the direct action of 

 the medium "was much more important as a "primordial 

 factor of organic evolution " than in later days. 



The Protozoa and Protophyta are evidently much less 

 emancipated from their environment than higher forms. 

 They are saturated by their surroundings in a sense which 

 cannot be maintained of higher unities except in their 

 germinal stages, and they are well known to be impressible 

 to a degree impossible in the higher animals and plants. 

 On the other hand, many of the higher organisms live in a 

 more complex environment, with which they are connected 

 in subtler and more numerous relations. Claude Bernard 

 (247) distinguished three degrees of independence in relation 

 to the environment — (1.) latent life, as in seeds, germs, 

 encystations, and desiccated organisms ; (2.) oscillant life, as 

 of plants in winter, or of hybernating animals; and (3.) 

 constant life, as of higher organism. 



Another contrast is very evident. Passive forms, like 

 sponges and algse, corals and trees, are much more in the 

 grip of their environment than are active forms like insects 



