102 THE DOCTRINE OF DESCENT. 



foundation, on a mystery, ought to be proscribed from 

 science for evermore." 



Without owning allegiance to any theory whatever, 

 we are constrained to recognize the fact, that in various 

 groups of organisms there even now exists such an in- 

 stability of form, and such a degree of variability, that 

 it is patent how constrained and artificial is their sys- 

 tematic separation. In many other groups, in most or- 

 ders of the Mammalia, for example, this phase of mobility 

 has been replaced by a certain quiescence, and the forms 

 now presenting themselves for observation, and com- 

 parison are so well defined from one another, that 

 they fit into the system without difficulty as " good spe- 

 cies." But if the " good species " are to be judged by 

 the experiences made in regard to the " bad " ones, and 

 if the preposterous hypothesis is not laid hold of, in con- 

 travention to all healthy human understanding, that 

 " good species " originated in a miraculous manner in- 

 accessible to our cognition, whereas the " bad species " 

 are susceptible of analysis, — the other alternative alone 

 is possible, that, as Haeckel says, if we knew them thor- 

 oughly, all species without exception would, in the sense 

 of the species-makers, be " bad species." We are also 

 acquainted with a sufficient number of bad species to be 

 capable of inferring the general law with certainty. 

 Nevertheless, all further corroboration and discovery of 

 bad species is acceptable. Regarded formerly by the 

 systematists only as incumbrances and as stones rejected 

 by the builders, they have now become the corner-stones 

 of science. 



Is species therefore, we again inquire, to be entirely 

 abandoned? Not so, for several reasons. Even assum- 



