varieties as there are possible combinations in crossing.
To account for the striking development of varieties of pigeons from the common type, it is only necessary to assume that in the first place not only one variety was formed, but that several were created, which eventually blended into one kind. This seems possible as we need only to remove artificial crossing by the fancier when the developed varieties will revert to a common type. Yet it is not necessary to assume this occurrence of the mixing of varieties, however probable, for the pigeon is composed of many essentials or traits blended in a common unit. In the pigeon, as in many other animals, the traits are marked and sensitive to selected breeding. That tendencies may be selected and developed to the ascendency is a sufficient explanation of the developed variety of any given species. From the wild grape or strawberry, developed and varied fruit is obtained. Withdraw cultivation, and they quickly revert to the wild varieties. The development is due to increased nutriment, cultivation, superior conditions for growth, and the favoring of selected tendencies. It is not due to any extraneous law, but is natural to the form itself. The cause of the possible development of varieties from common parentage now resides in the varied tenden-
