When I saw the article I wrote in print in the last number of Gardeners' Monthly, regarding the Blackman plum, I noticed that I did not say just what I wanted to say. It was my intention to say that the glands on this hybrid variety or mule are much more prominent than on any species of plum with which I am acquainted, but the reader would clearly infer from what I then said that glands do never occur on any plum. We know this to be different, for there is a slight development of glands on several species of Prunus and one in particular (Prunus glandulosa), found in southwestern Texas, has quite distinct glands all around the margin of every leaf but not upon the petiole in a prominent degree.

We will try to carefully experiment on the crossing of Amygdalus and Prunus this year. Perhaps we are not certain just how variations do occur and may often be the result of the work of some stray pollen carried by bees, and is thought to be variation induced by the variety within itself. Really, as I see it, we have very little positive knowledge on this subject except in the animal kingdom. There we know hybridization and sterility are quite closely connected, and that sterility is far more likely to occur in mules than in those cases in which species are not crossed. Pomologist U. S. Department of Agriculture.

[Mr. Van Deman gives the view of sterility in hybrids, as the view generally prevails. It is, however, a popular error, and has arisen from the fact that the hybrid between the horse and the ass does happen to be almost always sterile. Mr. Darwin has occasionally been quoted as authority for this sterile view of hybrids in general, but in a letter to the writer of this but a couple of years before his death, he utterly repudiated such a view, and stated that he was even then preparing a paper to show how very fertile some hybrid geese were. - Ed. G. M].