satisfactory explanation of the basis of this law will be possible only after the discovery of several new facts regarding the behavior and identity of the component parts of the reproductive cells. This same line of research has also been suggested by the more recent development of our knowledge regarding the accessory chromosome. Such research demands the use of the most perfected instruments and the exercise of the finest technique. It requires an impartial and truly scientific mind, and it is, therefore, very gratifying to find that most of the facts being added to our knowledge concerning hereditary processes in these connections are furnished by American investigators.
The Optimism of 1900
Within a very few years, after 1900, numerous investigators found the Mendelian law to be operative for a wide variety of characters and in many species of plants. Evidence was also forthcoming to show that the same was true of some characters of farm animals.
The air was filled with expectancy, for, since so many things were known to be inherited by Mendelian proportions, it was quite generally assumed that all inheritance was of the same kind. Breeding was no longer an art, nor even a science, but a simple application of mathematics. True, our knowledge of the modus operandi of all these occurrences was incomplete, but Mendel's law appeared to be the key to all facts of inheritance, and nothing of moment could be unknown for more than a few months. Such was the thought of many enthusiastic persons in 1902 and 1903. It seemed as though the great door was soon to be unlocked and reveal to us the truth that should explain all inheritance and all life, bringing a new era in biology and in the many vital studies of man with which biology is so intimately connected.
But even should the scientific explanation of Mendel's law be slightly delayed, there was no reason for the breeder of plants and animals to remain under the old régime; so it seemed to many careful and earnest workers in agricultural lines. The fact that the derivation of the formula was obscure was no hindrance to its utility.
One outcome of the new thought was the organization of the American Breeders' Association. The membership of this association comprised botanists, zoologists, florists, seedsmen, growers of seed com and other cereals, and also breeders of all classes of farm animals. The time was ripe for such an organization. It was the idea of some of the founders that the spread of the new science would revolutionize breeding practise.
At the second annual meeting of the American Breeders' Association, held in 1905, there were presented such papers as these: "Recent Discoveries in Heredity and their Bearing on Animal Breeding."
This paper was presented by Dr. Castle, of Harvard, a most capable