Page:Popular Science Monthly Volume 66.djvu/212

208 pissadi), of which there was no other specimen in America, it was grafted on to the Kelsey plum, a variety of Prunus triflorus. The graft itself did not bloom, but the presence of the graft brought about in the tree a cross of the two species. This is the only case known to me in which the graft affected the reproductive system of the plant, forming a cross between forms which had never crossed. Many hundred descendants of this cross are now living. Darwin accepted with reservations the account of the graft hybrids in potatoes, and there still remains some doubt of reliable testimony of the supposed fact. He also speaks of a now well-known graft hybrid of a yellow and purple cytisus, which is perhaps the most remarkable fact in this line on record."

All these varying states shade off from one to the other, with few hard and fast lines of separation.