PANGENESIS. 167 



a totally different developmental history. Hence we 

 are led to believe in the complete independence of 

 " each structure from that which precedes and follows 

 it in the course of development." 



The functional independence of the elements or 

 units of the body. Variability and inheritance. 

 Variability generally results " from changed conditions 

 acting during successive generations." The influence 

 is exerted on the sexual system, and if extreme, im- 

 potence tends to be produced. Bud-variation proves 

 that " variability is not necessarily connected with 

 the sexual system." The inherited effects of use and 

 disuse of parts imply that the changes in the cells 

 of a distant part of the body affect the reproductive 

 cells, so that the being produced from one of these 

 cells inherits the changes. " Nothing in the whole 

 circuit of physiology is more wonderful." 



" Inheritance is the rule and non-inheritance the 

 anomaly." Inheritance follows laws, such as the 

 tendency for a character to appear at corresponding 

 ages in parent and offspring. Reversion " proves to 

 us that the transmission of a character and its 

 development .... are distinct powers." Crossing 

 strongly induces reversion. " Every character which 

 occasionally reappears is present in a latent form in 

 each generation." 



The hypothesis of pangenesis attempts to explain 

 and connect together all the facts and conclusions 

 which have been summarised in the preceding pages. 



