216 eLASSlE^ICATlOl^. [Chap. XlV. 



important character of the length of the beak, yet all 

 are kept together from having the common habit of 

 tumbling; but the short-faced breed has nearly or quite 

 lost his habit: nevertheless, without any thought on 

 the subject, these tumblers are kept in the same group, 

 because allied in blood and alike in some other respects. 



With species in a state of nature, every naturalist has 

 in fact brought descent into his classification; for he 

 includes in his lowest grade, that of species, the two 

 sexes; and how enormously these sometimes differ in 

 the most important characters, is known to every natu- 

 ralist: scarcely a single fact can be predicated in com- 

 mon of the adult males and hermaphrodites of certain 

 cirripedes, and yet no one dreams of separating them. 

 As soon as the three Orchidean forms, Monachanthus, 

 Myanthus, and Catasetum, which had previously been 

 ranked as three distinct genera, were known to be some- 

 times produced on the same plant, they were imme- 

 diately considered as varieties; and now I have been 

 able to show that they are the male, female, and herma- 

 phrodite forms of the same species. The naturaUst in- 

 cludes as one species the various larval stages of the 

 same individual, however much they may differ from 

 each other and from the adult, as well as the so-called 

 alternate generations of Steenstrup, which can only in 

 a technical sense be considered as the same individual. 

 He includes monsters and varieties, not from their 

 partial resemblance to the parent-form, but because 

 they are descended from it. 



As descent has universally been used in classing to- 

 gether the individuals of the same species, though the 

 males and females and larvse are sometimes extremely 

 different; and as it has been used in classing varieties 



