120 VARIOUS OBJPX'TIOXS. Chap. IV. 



cation liuviu^ bjcn cficctcd sinco the f^lacial iicriocl would ha 

 of some avail ag'ainst those who believe iu an innate and 

 necessary law of development, l:)ut is powerless against the 

 doctrine of natural selection or the survival of the fittest, which 

 implies only that variations or individual differences of a favor- 

 able nature occasionally arise in a few s])ecies, and are then 

 preserved. 



It has been objected, if natural selection be so powerful 

 an agent, why has not this or that organ been modified and 

 improved? Why has not the proboscis of the hive-bee been 

 lengthened so as to reach the nectar of tlie red-clover ? Why 

 has not the ostrich acquired the power of llight ? But grant- 

 ing that these parts and organs have varied in the right direc- 

 tion — granting that there has been time sufficient for the slow 

 work of natural selection, the effects being often checked, as 

 they will be by intercrossing and the tendency to reversion, 

 who will pretend that he knows the life-history of any one 

 organic being sufficiently well to say that any particular change 

 would be, on the whole, to its advantage ? Can we feel sure 

 that a long proboscis would not be a disadvantage to the bive- 

 bee in sucking the innumerable small flowers which it fre- 

 quents ? Can we feel sure that a long proboscis would not, 

 by correlation, almost necessarily give increased size to other 

 parts of the mouth, perhaps interfering with the delicate cell- 

 constructing Avork? In the case of the ostrich, a moment's 

 reflection will show what an enormous supply of food would 

 be necessary to supply force for this bird of the desert to move 

 its huge body through the air. But such ill-considered objec- 

 tions are hardly worth notice. 



The celebrated paleontologist, Bronn, at the close of his 

 German translation of this work, asks, how, on the principle 

 of natural selection, can a variety live side by side with the 

 parent-species ? If both have become fitted for slightly-differ- 

 ent habits of life or conditions, they might live together ; 

 though, in the case of animals which freely cross and wander 

 much about, varieties seem to be almost always confined to 

 distinct localities. But if we put on one side polymorphic 

 species, in which the variability seems to be of a peculiar na- 

 ture, and all mere temporary variations, such as size, albinism, 

 etc., the more permanent varieties are generally fmmd, as far 

 as I can judge, inhabiting distinct stations, high land or low 

 land, dry or moist districts, or distinct regions. Bronn also 

 insists that distinct species never differ from each other only 



