342 ANIMAL BIOLOGY 



having been bridged, life gradually advanced from the 

 simplest particles of living substance to the highest types 

 of plants and animals. The establishment of the doctrine 

 of evolution was one of the greatest of the scientific achieve- 



FIG. 232. Charles Darwin. (From Gager.) 



ments of the igth century; and the credit for it is due, more 

 than to anyone else, to the great English naturalist, Charles 

 Darwin, whose epoch-making work, the Origin of Species, 

 published in 1859, first convinced the scientific world in 

 general of the truth of the evolution theory. 



