794 THE POPULAR SCIENCE MONTHLY. 



tioned involves the assumption of the following changes : (1) Th6 

 disappearance of all but one of the pistils ; (2) reduction of the 

 number of seeds ; (3) the abandonment of dehiscence ; (4) increased 

 hardness of seed coat; (5) the acquirement of succulence; (6) the 

 development of an attractive color. 



The first-named alteration we have already considered in con- 

 nection with the evolution of the flower. As with this, so with 

 the other changes, the best we can do is to imagine how they might 

 have come about. Now, it is true of all cajjsular fruits that until 

 fully ripe they are neither dry nor dehiscent. We know that 

 variations in the time of ripening do occur, and experiments have 

 shown* that even unripe seeds will germinate and produce strong, 

 healthy plants. In view of these facts it seems reasonable to sup- 

 pose that not only might there arise varieties in which the capsule 

 would retain something of its succulence until the seeds were 

 nearly ripe, but if the fruit in this condition were eaten by birds or 

 other animals the seeds might be disseminated by them, much to 

 the benefit of the favored variety. There were doubtless seasons 

 of scarcity in prehistoric times as well as now, when animals 

 would be glad of even such comparatively unattractive fruits as 

 we have described. Among the descendants of those plants whose 

 fruits had become somewhat berrylike, those having the more 

 succulent pericarp would, other things being equal, have most 

 descendants, and thus in the course of many generations the 

 present condition be reached. 



The conspicuousness, depending as it does upon the same 

 changes in the original pigment as occur in the transformations 

 of chlorophyll in autumn leaves, may be looked upon as a result 

 incidentally connected with the retention of succulence in the 

 pericarp after growth had ceased, and as this tendency for the 

 fruit to assume a color contrasting with the foliage would be 

 beneficial as an advertisement to birds, natural selection would 

 favor rather than hinder it. 



The fact that in mahonias the berries are commonly of a dark 

 purplish blue suggests that possibly this was the color first as- 

 sumed by the fruit of the genus, the more conspicuous scarlet of 

 the common barberry and its near relatives being acquired later, 

 along with the higher differentiation of structure which it accom- 

 panies. Although this view gains some support from the occa- 

 sional appearance of a blue-fruited variety of Berheris vulgaris 

 (which might be thought of as a reversion to the ancestral type), 

 still it should be remembered that our knowledge of the chemistry 

 of plant pigments is at best too meager to justify much confidence 

 in any theory of color change. 



* Goodale, Physiol. Bot., p. 460. 



