i8z THE POPULAR SCIENCE MONTHLY. 



same way that the infant passes from birth to manhood. That was, 

 I say, the vulgar opinion, but, in laying before our eyes the develop- 

 ment of the individual, God has given us a revelation of the course 

 of life by the world. 



The evolutionary history of animals establishes that there is not 

 this homogeneousness of development, but that the higher pass 

 through the forms of the lower; that the mammal, for instance, 

 passes through stages at which the lower vertebrates remain fixed. 

 All are therefore pursuing a journey along the same road, though 

 some may travel to a longer, some to a shorter, distance. There is 

 thus a parallelism between individual and race development ; a close 

 connection between the phases of development in the individual and 

 in the species. 



The type of each animal is from the first as it were imbedded in 

 the embryo and controls its evolvement. The embryo never makes 

 any attempt to change from one type to another, but sometimes the 

 tendency to a form and not the form itself is transmitted. 



The parallelism that exists between the career of the individual 

 and the career of the race reappears in the life of the world. There is 

 a resemblance indeed more than a resemblance between the succes- 

 sive forms through which man himself in his prenatal life has passed, 

 and those that have appeared in myriads of ages in the biography of 

 the earth. Common-sense revolts against the idea that these trans- 

 formations are in the individual due to divine intervention. In that, 

 and in the case of the earth, they must be due to natural law. 



In the year 1859 there was published by Mr. Darwin a work on 

 "The Origin of Species by Means of Natural Selection, or the Preser- 

 vation of Favored Races in the Struggle for Life." 



In this, and in other subsequent works, it is shown that the indi- 

 viduals of each species tend to increase in a very rapid ratio an in- 

 crease more rapid than that of their means of subsistence. Each has, 

 therefore, to contend with his competitors ; and hence all must exhibit 

 " a struggle for existence." 



CTCT 



But modifications are incessantly taking place in the form and 

 characteristics of individuals, giving to some an advantage, to some 

 a disadvantage, as compared with their competitors. Hence, the for- 

 mer will prevail, the latter will succumb in the struggle. This in 

 the language of the hypothesis is formulated " the survival of the 

 fittest." 



And as the pigeon-fancier or other person who devotes himself to 

 the breeding of animals can produce any form he wishes by selecting 

 its progenitors and pairing them together, exercising thus artificial 

 selection, so if any of the chance-forms that have arisen should be 

 better adapted than others for perpetuation, they will be perpetuated, 

 or Nature may be said to have made a selection. Hence the term 

 "natural selection," which has been made to designate this hypothesis. 



