ore the pistillate gets ready. Sometimes we have a plant that is self
sterile. I have experimented with pollen from several different nut
trees and also with the Norway spruce. Then again, there are abnormal
cases; sometimes there is parthenogenesis. The jimson weed is the first
plant which has ever been reproduced by parthenogenesis. Since that was
discovered, an investigator in California has found a similar case in
fruit developed without pollination.

One of the most important conceptions in heredity is its effect upon
characters and factors. Take the Japanese bean here shown for example,
one dark bean and one mottled. In the next hybrid generation we find
three mottled and one dark. That is the familiar "three to one" ratio of
Mendel's law. We believe now, that all, or at least a very large
proportion of the heredity characters in plants of all kinds may be due
to a series of factors; but the habit of growth of the plant is due to a
single factor. We have the case here of a second generation of the
weeping mulberry that I crossed with the white mulberry. As a result
there was an average of three erects to one weeping one. Certain
characteristics may be made up of the inter-action of a large number of
factors. This will give a little idea as to the complexity of Mendel's
law.

How do we get new characters in nature? New types are due to the
rearrangement of previously existing characters, just as with the
old-fashioned kaleidoscope, where you turn the crank and get new
pictures. Another way is by the sudden appearance of new factors.

I wish to speak about one effect of hybridization, which is really
connected with heredity factors, the vigor which occurs when we cross
different varieties, species, or even races. In my experience certain
types that have been naturally contrasted finally lose vigor, and after
two or three generations the plant disappears. Then again I could show
you cases where yields are greatly increased due to hybridity. These are
established facts, not only as regards species of plants and trees but
also as regards the human race. Hemy, in Dublin, who has done the best
work in this line of endeavor, believes that many of our more
rapid-growing trees are rapid-growing because they are hybrids.

To summarize, I have tried to point out the fact that diversity which we
see in nature is real, and that it is brought about by two causes,
namely, environment, and heredity. And that heredity is brought