The admission which I least like among your familiar illustrations is that while the various pigeons have descended from one stock the dogs have come from two or more species¹

It seems to me that an occasional cross with some one of the several wolves, the grey & the prairie wolf or even perhaps some foxes & more distant species of the canine genus would have served all the purposes you require. Let these have been more frequent than in the case of most domestic animals, let the hybrid have always interbred with one of the pure parent stock but the infusion of the foreign blood into the domesticated wolf, or whatever single species the dog came from, may have given rise to a tendency to reversion to some of the ancestral crosses why should not they satisfy all your well-ascertained facts, leaving your canons of variation & hybridity unshaken. It is for the followers of Pallas to prove their opinion by some facts. The period of gestation of the dog & the wolf, if as constant as Bell believes, is a strong argument.² As Bransby Cooper was a six month’s child,³ I doubt not you can find great occasional irregularity in the gestation of domestic animals & of Man—but still it is surely worth a good deal.—⁴