TxEYIEWS. 
177 
turkeys, and gold fish. Pigeons and rabbits form, perhaps, the best examples 
•of the immense influence of artificial selection in the production of new 
organic forms. This is because the selection and breeding of these animals 
have been made so much of an art and science, and because the history of the 
several breeds is so well and fully recorded. Taking the group of pigeons, 
and studying the history of its origin, Mr. Darwin, it seems to us, shows 
conclusively that the 150 different kinds have all descended from one 
common progenitor, the Columha livia, or rock pigeon. This is a great point 
to have demonstrated, for it is nothing less than this, that man, by carefully 
watching the variations of the several generations of pigeons, and selecting for 
reproduction those which possessed the features required for perpetuation, 
has succeeded in establishing a number of families of pigeons as different 
from each other as from the primal parent, as capable of regeneration as any 
natural species, and exhibiting anatomical peculiarities which, if seen in 
feral animals, would at once justify the naturalist in regarding such animals 
as perfectly distinct species. The osteological results of this artificial selec- 
tion are not so important in pigeons as in other domestic creatures ; still, 
even on this point they are by no means insignificant. For example, we find 
even the total number of vertebree — a formidable specific feature — modified j 
in the rock pigeon, the total number being 39, it is 42 or 43 in the Pouter, 
whilst in the Dutch Roller it is only 38. The total of observed modifications, 
as summed up by Mr. Darwin, is as follows : — 
To sum up, we may confidently admit that the length of the sternum 
and frequently the prominence of its crest, the length of the scapula and 
furculae have all been reduced in size, compared with the same parts in the 
rock pigeon ] and I presume that this may be safely attributed to disuse or 
lessened exercise. The wings, as measured from the ends of the radii, have 
likewise been generally reduced in length; but, ovdng to the increased 
growth of the wing-feathers, the wings from tip to tip are commonly longer 
than in the rock pigeon. The feet as well as the tarsi, conjointly with the 
middle toe, have likewise in most cases become reduced ; and this, it is pro- 
bable, has been caused by their lessened use ; but the existence of some sort 
of correlation between the feet and the beak is shown more plainly than the 
effects of disease.” 
We cannot dwell upon the other points of anatomical difference which 
the author describes. We must, therefore, pass on to his reasons for 
believing that all these several varieties have descended from a common 
stock. These reasons are: — First, the improbability that more than one 
wild species should still exist somewhere unknown to ornithologists, or 
that they should have been extinguished within the historical period; 
secondly, the improbability of man having in former times thoroughly 
domesticated as many different species as there are breeds at the present 
day ; thirdly, the unlikelihood of man’s selecting several abnormal species ; 
fourthly, the fact that all produce mongrels ; fifthly, the important fact 
that all these races, whether crossed or not, occasionally revert — throw back, 
as breeders say — to a form which more or less closely resembles what Mr. 
Darwin regards as the ancestral type, the C. livia. 
Rabbits present us with another remarkable example of the production of 
divergent forms by the influence of artificial selection. As in the case of 
