NATUEAL SCIENCES OF PHILADELPHIA. 301 



At the conclusion of my paper on the Imos of adnalion, read before the 

 meeting of the American Association for the Advancement of Science, at 

 Chicago, Dr. J. S. Newberry kindly pointed out that, in a fossil state, Gh/p- 

 tostrobus and Taxodium were often found side by side, but always with so much 

 difference between the scales of the cones that, while assenting to the general 

 principles of the paper, he could not regard these two plants identical. As 

 cones are nothing more than metamorphosed stems and branches, it is not sur- 

 prising that the sames laws of adnation which might operate in making the Taxo- 

 dium Glfiptostrohus, and which make them look so very distinct in the different 

 stages of adnation, should also operate on the fruit, and make it appear, when 

 at the widest point of divergence, as really different. It should in fact do so, 

 and instead of the differences in the cones of these fossils being any proof of 

 their specific distinctness, it must be received as a natural sequence of the law 

 I would evolve. 



The specimens I now exhibit show at any rate that the two plants are identi- 

 cally the same. This granted, it completely refutes the generally received 

 theory, that no one species of Conifera? inhabits at once the eastern and western 

 worlds. 



In my paper on variations in Epigsea repens, presented for publication last 

 May, I endeavored to show that "cultivation " and "external circumstances" 

 would not account for variations in form to the extent they usually received 

 credit for; but that there was rather a regular principle of growth in form, as 

 well as in substance, independent of outward agencies, which agencies were 

 calculated quite as much to preserve as to originate the growing forms. 



Those accustomed to study chiefly from herbaria, and little from living spe- 

 cimens, have no idea of the great variations from one type which many species 

 present. These comparative differences are often so insensibly blended, that 

 it is only when we meet with some very extreme forms that they attract our 

 attention, and then only to note their extreme differences. Even when noted 

 they are contemned as obstructing classification, rather than welcomed as 

 invaluable aids in resolving the laws of form. 



In a recent review of part 16 of Decandolle^s Prodromus, which has lately ap- 

 peared, with the Coniferffi by Prof Parlatore, the reviewer says : " It must be 

 clear to every one that a great number of so-called species are varieties of one 

 strain, doubtless produced by localization in different climatal or natural conditions." 

 {Gardener's Chronicle, page 922, 1868.) As this review is understood to be by 

 one who is himself known as a describer of many Coniferte, which are doubt- 

 less varieties of one strain, it may be worth while to point out, in some Coni- 

 ferit. that neither climatal nor any external condition has as much to do with 

 variation in form as an innate power of development, independent of either 

 climatal or local causes. 



In one of our commonest pines — Pinus inops — a very careful comparative ex- 

 amination will show scarcely any two trees to be exactly alike ; the habits of 

 the tree, the shade of color, or the length of the leaves, the size or form of the 

 cone, the scales, or the seeds — in some one point a difference may be found 

 which can easily be described in words. When extremes are brought together 

 the differences are quite as great as characterize different species. By descrip- 

 tions alone they would be fairly entitled to rank as distinct. The mind fails 

 to unite them. It is only the educated eye which perceives their identity. I 

 exhibit two cones from two trees growing on the banks of the Susquehanna, 

 near Harrisburg. One is very long and narrow — three and a half inches in 

 length, by only three-fourths of an inch wide at the base, and the scarcely 

 projecting scales barely spinescent, the other nearly as wide, but only 

 half the length, and with strongly projecting scales and spines. Unless 

 with previous acquaintance of Hinus inops in its natural places of growth, a 

 botanist might well be pardoned for considering these distinct species, yet with 

 the multitude of intermediate forms, all under the same external conditions, 

 how can any " localizatious " account for the varieties ? I have the same ex- 



1868.] 



