This section is from the book "The Gardener's Monthly And Horticulturist V26", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The currant of the grocers is a grape known as the Corinth, from which the name currant is derived. It has no seeds. If it had seeds the berries would probably be double the size. At least in our ordinary varieties of hothouse grapes we often find seedless ones among the others, and these are not half the full size. These are probably from female flowers which have either not been fertilized at all, and yet have had power to develop to some extent, as we find in the Banana and some other fruit, or they may have had the use of pollen to some extent, and yet vital power was not sufficient to send the ovules forward. We believe it is not known exactly how the currant is formed.