1 64 MODERN IDEAS OF EVOLUTION 



In this Lc Conte follows the usual methods of Spencer 

 and Darwin. 



Under his second head he notices three laws 

 which he believes to be common to the above kinds 

 of development : (i) The law of differentiation is the 

 same with Spencer s law of progress from the homo 

 geneous to the heterogeneous, and is, though in dif 

 ferent ways and degrees, characteristic of development 

 in general. (2) The second law is really a partial ex 

 ception to the first, and is called the law of progress 

 of the whole, the meaning being that, while on the 

 whole there is progress, a vast number of the lines of 

 development do not rise, but remain stationary or 

 retrograde. This law, be it observed, is one of those 

 which emphasise the difference between the natural 

 development of the embryo and those things with 

 which it is supposed to be analogous ; since, except 

 in rare cases of retrograde development, it docs not 

 occur in that of the individual, but it is so frequent 

 in the geological development, as to seem the rule 

 rather than the exception. (3) The third law is 

 applicable only to the third of the great kinds of de 

 velopment, and marks one of its distinctive characters. 

 It is that of rapid culmination and subsequent deca 

 dence of the great types of life. A diagram which 

 the author gives to show this is a curious illustration 

 to the eye of the fallacy of the doctrine of gradual 

 and continuous evolution as applied to geological 

 time. It represents, so to speak, successive waves in 



