Species and Varieties, Their Origin by Mutation by Vries, Hugo de, 1848-1935

It is readily seen, that in the ordinary form the lips are of a darker red than the tube. This evident dissimilarity indicates some complexity. And in fact we have two varieties which exhibit the two causes of this attribute separately. One of them is called "Delila," and has the red color limited to the lips, whilst the tube is pure white. The other is called "Fleshy," and is of a pale pink throughout the whole corolla. Adding these two units to one another, we get the original dark red of the wild type, and it may be briefly stated here, that the way of effecting such an addition is given us in the crossing of the "Fleshy" and the "Delila" variety, the hybrid showing the two colors and returning thereby to the old prototype.

Other cases of compound flower colors or of color patterns might be given as in the _Mimulus_ and the poppy, and in most of these cases some varieties are to be seen in our gardens which show only the single constituents of the group.

[152] Many dark flowers have an intermediate bright hued form besides the white variety, as in the case of roses, asters, _Nicandra_ and so on.

Intermediate forms with respect to stature may also be seen. The opium-poppy, the snapdragon, peas, the _Nicandra_, and many other garden-plants have not only dwarf varieties, but also some of intermediate height. These, though they are intermediate between the tall and dwarf types, cannot be considered as transitions, as between them and the extremes, intermediates are, as a rule wholly lacking. Instances of the same occurrence of three types may be seen in the seeds of maize ("Cuzco," "Horse-dent" and "Gracillima") of beans and some other plants. The _Xanthium Wootoni_, above referred to, with only part of the prickles of Xanthium commune is also a very curious instance of the demonstration of the compound nature of a character.

Summarizing the conclusions that may be drawn from the evidence given in this lecture, we have seen that varieties differ from elementary species in that they do not possess anything really new. They originate for the greater part in a negative way, by the apparent loss of some quality, and rarely in a positive manner by acquiring a character, already seen in allied species. These characters are not of the nature of [153] morphologic entities, but are to be considered as physiologic units, present in all parts of the organisms, and manifesting themselves where ever occasion is afforded. They are units in the sense that they may appear and disappear singly. But very often they are combined to yield compound characters, which are capable of analysis. Opportunities for such an analysis are afforded by these groups of cultivated varieties, of which some members show a single distinguishing quality, or a number of them.

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LECTURE VI

STABILITY AND REAL ATAVISM