XIII ADAPTATION AND SEED-BUOYANCY . 121 



Further testimony is adduced by this investigator (p. 182) in 

 supporting his view in the fruits of the genera Barringtonia, 

 Clerodendron, Cordia, and Guettarda, where the buoyant tissues 

 extensively developed in the coast species are either non-existent 

 or only represented by a trace in the inland species of the same 

 genus, a difference in structure associated with the loss or great 

 diminution of the floating capacity of the fruits concerned. I have 

 been able to establish other examples in the rases of the genera 

 Scaevola and Tacca, which will be found referred to in Chapter II. 



Professor Schimper (p. 200) points to the circumstance that the 

 " adaptations " in these fruits all belong to the diagnostic marks 

 of the genera and the species, and contends that these plants 

 abundantly prove the erroneous nature of the contention that 

 Natural Selection could have played no part in the elimination of 

 the strand-flora. My ov/n contention is that Natuial Selection has 

 played such a part, but that in doing so it has merely availed itself 

 of characters previously existing, without originating, modifying, or 

 improving them in any way. The foregoing evidence might with 

 equal fitness be employed to show, as pointed out in Chapter II., 

 that in the course of ages there has been a great sorting process by 

 which, excluding the mangroves, plants of the xerophilous habit 

 possessing buoyant seeds and fruits have been sorted out and placed 

 at the coast. Direct evidence does not lead us farther than to the 

 establishment of a littoral station for plants thus endowed. The 

 problem whether the characters of their fruits and seeds that are 

 concerned with buoyancy may be regarded as adaptive in the 

 Darwinian sense lies beyond the reach of direct testimony. We 

 can, however, approach it from the outside by several directions, 

 and from some of these we will now proceed to deal with it. 



There is first the singular circumstance that in Fiji, when the 

 littoral plants with buoyant seeds or fruits leave the beach and 

 extend far inland, they, as a rule, retain their floating powers 

 and, of course, their buoyant structures. I found this to be true of 

 Cassytha filiformis, Cerbera Odollam, Ipomea pes caprae, Morinda 

 citrifolia, Scsevola Koenigii, and one or two other plants mentioned 

 in Note 44, where this subject is discussed. My experiments 

 on these plants indicated that their fruits or seeds floated equally 

 long, whether obtained from coast or from inland plants. 

 This, at first sight, appears to present a serious objection to the 

 adaptation theory ; but it was not so regarded by Professor 

 Schimper, who in a letter to me, dated March 8th, 1900, observed 

 that he did not see " why littoral plants growing inland should lose 



