1864.] 42!» 



begin the Species, I am therefore irresistibly led to believe, that the 

 former gradually strengthen and become developed into the latter, and 

 that the diiference between them is merely one of mode and degree. 

 If a savage from some newly-discovered island in the Pacific Ocean 

 were shown for the first time in his life a large herd of horned cattle, 

 containing newly-born calves, half-grown calves, yearlings, heifers, 

 steers, cows and bulls of all sizes and ages, he would naturally, I think, 

 arrive at the conclusion that they were all modifications of one animal, 

 though he had no opportunity, as we have, to watch from day to day 

 the calf develop into the yearling, the yearling into the heifer, and the 

 heifer into the cow. So with the gradual development of the Variety 

 into the Species. We cannot, from the shortness of human life, see 

 the mime identical species develop gradually from century to century, 

 first into slight varieties, then into marked varieties, then into geogra- 

 phical or phytophagic races, then into new species ; but in one and 

 the same year we may see all the stages of development, with all the 

 possible intermediate grades, in different species ; and to shut our eyes 

 to the validity of this the only possible proof under the circumstances, 

 and to maintain that Species were created and Varieties have made 

 themselves, and that the two categories are therefore essentially dis- 

 tinct, is as if the imaginary savage from the South Seas, ignoring or 

 overlooking the presence of the yearlings and heifers, were to come to 

 the couclusiou that calves and cows are distinct species of animals. 

 Darwin never spoke a truer word than when, referring to certain natural- 

 ists who believed in the essential difference between Species and Varie- 

 ties, and yet published the very same ideLtical form one year as a Variety 

 and the next year as a Species, he said that " the day will come, when 

 this will be given as a curious illustration of the blindness of precon- 

 ceived opinion." {Orig. Sp. p. 419. Am. edit.) 



Rock Island, Illinois, October 24, 1864. 



POSTSCRIPT. 



In my Paper in the Proc. Bost. Soc. Nat. Hist. (p. 289), referring 

 to the fact that Dr. Harris saiys that the Caterpillar of Ilalesidota tes- 

 Uaris '• is not correctly represented in Smith and Abbott's Insects of 

 Georgia," 1 suggested that •' possibly the Caterpillar of Antiphola may 



se 



