and the Siberian raspberry. Both have small and insignificant fruits, while the hybrid on this point greatly surpasses either parent. In Europe we have long known similar instances through the studies of wild hybrids by Kerner, and by Wichura, Janzewsky and many other writers regarding cultivated bastards.
If the relationship between species is not close enough, all attempts to hybridize are frustrated. Either the crossing is a failure, and no seeds are produced, or hybrids are obtained which are infertile. In the case of flowers this is not of so much importance, but in regard to fruit trees such a result is a complete failure. It is evident that nature has here drawn a limit which man can not cross. This boundary line is, however, not marked, and consequently once in a while surprising results are obtained. Hybrids which are infertile in thousands of cases may for once prove a success among hundreds of thousands. Burbank has an example of this in his crossing of Petunia with tobacco. From numberless hybrids he got one germinating from seed. He named this curiosity Nicotunia (from Nicotiana and Petunia). It was not very attractive and succumbed after one year, having flowered profusely, but failed to produce any seed.
It is unfortunate that we can not see this limit of nature in advance, but have to learn it by experience. And this experience includes an almost incomprehensible amount of labor of which no one hears anything.
