xi, c, 4 Copeland: Natural Selection 151 



not proved of any special value to its possessors, and is probably a more 

 recent development. There are many other so-called adaptations in many 

 other families which can be dealt with in the same way. Always the 

 figures go to show that evolution of forms is on the average indifferent, 

 and that these so-called adaptations are of no special advantage to their 

 possessors." 



Now, if we agree that the Rubiaceae with fleshy fruits are 

 more recent than those with dry fruits, this alone might be 

 responsible for the greater abundance of species with dry 

 fruits, in spite of more perfect adaptation on the part of those 

 with fleshy fruits. In reality, however, this does not hit the 

 kernel of the matter. The fact is that the dry fruit is also an 

 adaptation, just as much as is the fleshy fruit. One is adapted 

 to one set of conditions, the other to another set, and the two 

 sets of conditions may perfectly well be encountered at the same 

 time and in the same place. A perfectly parallel situation is 

 presented by the structure of the pileus of the Agaricales. As 

 Buller has beautifully shown in the Pfeffer Festschrift, most 

 of the species of Coprinus have one type of structure and beha- 

 vior, while Psalliota and nearly all of the other Agaricaceae have 

 a different type, the two differing in almost all possible details, 

 even down to the finest, but both being recognized by Buller 

 as highly and appropriately specialized, the two occurring side 

 by side without the slightest prospect that either will drive 

 the other out. 



It is important to each group of plants, for the sake of the 

 completest possible success in holding what place it has and in 

 spreading, that it occupy every available habitat, make use of 

 every available means of dispersal, and make the most of each 

 factor that will insure the reproduction of any of its members. 

 The fact that some Rubiaceae are adapted to dispersal by the 

 characters of their dry fruits does not make it at all a dis- 

 advantage that related plants of the same family be adapted 

 to the same end by the possession of fleshy fruit. The family 

 is better off with two general methods than it would be with 

 one general method. In each generation, the family as a whole 

 is safer because every possible method is taken advantage of 

 by some of its members. The members that scatter their seeds 

 by the medium of fleshy fruits are, in this respect at least, out of 

 competition with those that scatter their seeds by methods 

 depending upon the dryness of their fruit. To this extent, the 

 family can have more members and be more successful, because 

 in this respect competition within the group is removed. 



