1886.] NATURAL SCIENCES OP PHILADELPHIA. 295 



towards an ultimate oak or a chestnut, as the case may have been. 

 But when we take the subsequent changes the evolution of the 

 species of oak, and the species of chestnut, each class from its 

 primordial oak or chestnut, and observe the same parallel lines 

 of change in each, it is difficult to conceive how this exact paral- 

 lelism could have come about except under a fixed law of change, 

 which provides that when changes occur they shall be in strict 

 accordance with a prior plan by which nature herself is bound 

 laws by which, if we could only ascertain them, we could ourselves 

 foresee and define the forms that are yet to be a thousand years 

 beyond our time, and which no mere accidents of environment 

 could alter or delay. 



The oaks exhibited, though when we have the fruit we can see 

 they are oaks, have the foliage so like the chestnut that it is 

 difficult to determine them. The dwarf species from China is so 

 nearly like a chestnut, that only by the absence of the setaceous 

 teeth that edge the chestnut leaf, can we see any difference. But 

 the leaves are of a thicker texture than the other chestnut oaks 

 the serratures are finer and closer together, and the undersurface 

 of the leaf is cinereous, while the chestnut oaks exhibited in com- 

 parison are of the same tint on both sides. 



Now we take the chestnuts. We have the larger growing 

 species as we have the larger growing chestnut oaks the leaves 

 are light green on both sides, and vary in the toothing, just as 

 the chestnut oaks do variation in each class is exactly parallel. 

 The parallelism extends to the formation of a dwarf species. We 

 have a dwarf chestnut, Castanea pumila,]nst as we have a dwarf 

 chestnut oak, Quercus chinensis, and the parallelism extends to 

 the sub-characters, for the dwarf chestnut, the chinquapin, has 

 leaves of a thicker texture, the serratures are finer, and the under- 

 surface of the leaf is cinereous, while the chestnuts exhibited are 

 of the same tint on both sides. 



Mr. Meehan finally remarked that the facts seemed to him 

 stronger arguments in favor of evolution than many usually 

 offered. That the changes in two very distinct genera that we 

 only assumed to be syngenital, should be so nearly of a parallel 

 character in each, is proof they were carrying out a plan originally 

 common to both. While the fact that these original provisions, 

 as we must regard them, for these special forms have been so 

 faithfully carried out the one on the American continent, the 

 other in Eastern Asia despite the varying conditions of mere 

 " environment," shows how light a factor external circumstances 

 are in the evolution of forms. 



July 20. 



Mr. Thomas Meehan, Yice-President, in the chair. 

 Thirteen persons present. 



