340 Organic Nature s Riddle 



views as to what we are all agreed to regard as at least an 

 iraportant factor in the origin of species. No less a person 

 than Mr. Wallace has written the following significant 

 words : — 



* No thoughtful person can contemplate without amazement the 

 phenomena presented by the development of animals. We see the 

 most diverse forms — a mollusk, a frog, and a mammal — arising from 

 apparently identical primitive cells, and progressing for a time by 

 very similar initial changes, but thereafter each pursuing its highly 

 complex and often circuitous course of development with unerring 

 certainty, by means of laws and forces of which we are totally 

 ignorant. It is surely a not improbable supposition that the 

 unknown power which determines and regulates this marvellous 

 process may also determine the initiation of these more important 

 changes of structure, and those developments of new parts and 

 organs which characterise the successive stages of the evolutions of 

 animal forms.' 



These words advocate and confirm what I have elsewhere 

 antecedently urged. Many influences doubtless may come 

 into play in the origin of new species ; but let us look a little 

 narrowly at certain influences which rfiust come into play 

 therein, and the action of Avhich no man can deny. 



One of these influences (which no one has more richly 

 illustrated than has the late Mr. Darwin) is that of heredity ; 

 but what is heredity ? 



In the first place it is obviously a property, not of new 

 individuals, not of offspring, but of parental forms. As every 

 one knows, it is the innate tendency which each organism 

 possesses to reproduce its like. If any living creature, Xy 

 was self-impregnating and the outcome of a long line of 

 self-impregnating predecessors, all existing in the midst of 

 one uniform and continuously unvarying environment, then 

 X would produce offspring completely like itself. This 

 fundamental biological law of reproduction may be com- 

 pared with the physical first law of motion, according 



