DAEWIN ON NATUEAL SELECTION. . 99 



herent tendency for betterment — for improvement; and he 

 calls this principle, natural selection. It is most strikingly- 

 manifested in all organic beings in their constfftit " struggle 

 for existence," and is happily expressed in the phrase often 

 used by writers, "the survival of the fittest." 



Now we maintain that this same principle not only harmon- 

 izes with, but is nothing more nor less than the great law of 

 propagation, based upon the perfectionism of all organization ; 

 and what are denominated "Laws of Variation" by Darwin, 

 and which he has discussed extensively, may be fully ex- 

 plained by the laws of hereditary descent. When we take 

 into consideration the fact that the ti'ue law of propagation is 

 based upon a perfect standard in nature, all changes or devia- 

 tions from that standard or model come under the law of in- 

 heritance. With this explanation it will be seen at once that 

 a wide and varied field is laid open for its operations. It is 

 subjected to a great variety of conditions, not only witliin the 

 body itself, but to numerous external agents, such as climate, 

 food, exercise, etc. At first thought there are so many anom- 

 alous cases, so many apparently contradictory facts and sec- 

 ondary agents, it would seem almost impossible to arrange 

 them all under any one general principle. But the more 

 carefully the whole subject is examined from difierent points 

 of view, the more clearly, we think, it will appear, that this 

 classification of facts, this explanation of phenomena can be 

 reduced to a general system. This position of things may be 

 illustrated by the history of other sciences, in which there 

 were periods when great masses of facts had been accumu- 

 lated, and many and long discussions had been held without 

 much satisfaction ; but just as soon as some leading principle 

 had been discovered, all these facts and theories come into 

 Ime, and receive a satisfactory explanation. If the immense 

 collection of facts gathered by Darwin in his book on " Varia- 

 tion of Animals and Plants " is carefully analyzed and classified, 

 according to the two great laws of propagation and heritage, 

 they become not only far more intelligible, but afford strong 

 evidence of the truth of these principles. In fact, we have 

 found in Darwin's contributions to science, a great storehouse 

 of facts ; a grand accumulation of evidence in proof of some 

 views upon the law of population which we had entertained 



