HEAT AND COLD. 



is, the portion leading to the establishment of the hy- 

 pothesis. First, he never brought any proof to bear 

 other than within a given species, tending to show 

 crossing or change. Pigeons were intermarrying and 

 in consequence bettering the grade. Different families 

 of men intermarrying with each other, and in conse- 

 quence bettering the species. Dogs crossing with 

 dogs, and in consequence bettering the same. Horses 

 crossing and cattle crossing, but in each case crossing 

 with their own species. In all historic periods or 

 geologic periods he could not bring a case to bear 

 where one form of life could combine with another, 

 and after combining become prolific. He proves con- 

 clusively that it did not occur by reviewing all history 

 both earthly and human. 



But while he proves the absurdity of even chance 

 crossings, he brings into play the near resemblance of 

 properties in organic nature, taken as a chain from 

 smaller to higher grades. From the smaller forms 

 linking on close to the next higher grade until the 

 whole reveals one continuous change from bottom to 

 top. One property gradually bordering onto the 

 other. In this he has truly discovered that the whole 

 of nature was made by one law. But the law he knew 

 not, and acknowledges he knew not in his work, while 

 holding the hypothetical object in the foreground as a 

 means of carrying the mysterious all-devouring being 

 onward, by the pabulum he tends to reveal which will 

 assuage its gluttony. 



Should Darwin have actually been convinced of 



252 



