that the races of the dog differ in no important characters. A highly
competent judge, Prof. Gervais (1/73. 'Hist. Nat. des Mammif.' 1855 tome 2
pages 66, 67.), admits "si l'on prenait sans controle les alterations dont
chacun de ces organes est susceptible, on pourrait croire qu'il y a entre
les chiens domestiques des differences plus grandes que celles qui separent
ailleurs les especes, quelquefois meme les genres." Some of the differences
above enumerated are in one respect of comparatively little value, for they
are not characteristic of distinct breeds: no one pretends that such is the
case with the additional molar teeth or with the number of mammae; the
additional digit is generally present with mastiffs, and some of the more
important differences in the skull and lower jaw are more or less
characteristic of various breeds. But we must not forget that the
predominant power of selection has not been applied in any of these cases;
we have variability in important parts, but the differences have not been
fixed by selection. Man cares for the form and fleetness of his greyhounds,
for the size of his mastiffs, and formerly for the strength of the jaw in
his bulldogs, etc.; but he cares nothing about the number of their molar
teeth or mammae or digits; nor do we know that differences in these organs
are correlated with, or owe their development to, differences in other
parts of the body about which man does care. Those who have attended to the
subject of selection will admit that, nature having given variability, man,
if he so chose, could fix five toes to the hinder feet of certain breeds of
dogs, as certainly as to the feet of his Dorking fowls: he could probably
fix, but with much more difficulty, an additional pair of molar teeth in
either jaw, in the same way as he has given additional horns to certain
breeds of sheep; if he wished to produce a toothless breed of dogs, having
the so-called Turkish dog with its imperfect teeth to work on, he could
probably do so, for he has succeeded in making hornless breeds of cattle
and sheep.