If we bear in mind all these difficulties we cannot wonder at the confusion on this question that seems to prevail everywhere. Some authors following Linnaeus simply call all the subdivisions of species, varieties; others follow Jordan and avoid the difficulty by designating all smaller forms directly as species. The ablest systematists prefer to consider the ordinary species as collective groups, calling their constituents "The elements of the species," as was done by A.P. De Candolle, Alph. De Candolle and Lindley. By this method they clearly point out the difference between the subdivisions of wild species as they ordinarily occur, and the varieties in our gardens, which would be very rare, were they not singled out and preserved. Our familiarity with a character and our grounds for calling it an old acquaintance may result from two causes, which in judging a new [130] variety are essentially different. The character in question may be present in the given species or it may be lacking, but present in the other group. In the first case a variety can only be formed by the loss of the character, in the second case it arises by the addition of a new one. The first mode may be called a negative process, while the second is then to be designated as positive. And as it is more easy to lose what one has than to obtain something new, negative varieties are much more common than are positive ones. Let us now take an instance of a character that is apt to vary in both ways, for this is obviously the best way of making clear what is meant by a negative and a positive change.