NATURAL SCIENCES OF PHILADELPHIA. lOt 



all who studj^ this part of Botaii}-. I find that the^^ are not for 

 the duplicatiou of parts, but are separately organized from one 

 another. Thus, in Gratgxus and Gleditschia, the upper bud pro- 

 duces a spine, the slower is organized to grow as an axillary shoot 

 the next season. But the best illustration of the distinctive 

 organization is in those cases where both upper and lower buds 

 sometimes push the same season, as in Ifea, Lonicera^CaprifoKum, 

 or Halesia. Here we find that one is organized for floral organs, 

 and the other for axillary prolongation. The upper bud always 

 has the same function, and the lower its own, in the same species. 



A flower being a modified branch, in which the bract is the leaf 

 and the peduncle the axillary bud, it follows that the laws of 

 axillary stem-production will be more or less reproduced in the 

 inflorescence. 



Referring now to my paper on Adnation in Goniferse^ we found 

 that the true leaves of many genera in this order were adnate to 

 the stem, forming what some botanists have termed pulmni^ or 

 cushions, under the fascicles of some species of Pimis, and that 

 what are commonly called leaves, the " needles," are really phyl- 

 loidal shoots. An examination of Abies excelsa will show that 

 the upper portion of the needle has a different origin from the 

 lower adnated portion, or pulvinus, and that in all probability it is 

 a modification of the phenomenon referred to in Gymnocladus, 

 and other plants, of a longitudinal string of buds, in which the 

 upper is of a diff'erent organization to the lower one. In Larix 

 it was shown that in the verticils, or perhaps more properl}' spurs or 

 clusters, the true leaves were free, while in the elongated axis they 

 became for most of their length adnate with the stem, forming the 

 spathulate scales we find peel off" the two-3'ear-old wood. 



At the flowering time of the Larch, the male and female flowers 

 proceed from the termination of the spurs — not merely "of the 

 preceding year," according to Graifs llanual, but in some cases 

 of many preceding j^ears, " the sterile from leafless buds, the fertile 

 mostly with leaves below." (Gray^s llanuaJ, 5th ed., p. 472.) Why 

 have the female flowers leaves under them, and the male none? 

 Comparing the male and the female catkins, we see why. The scales 

 of the male are formed out of the leaves which become full}^ formed 

 in the female one. The pair of anther cells are thus simply on the 

 back of a transformed leaf, just as we find the spore-eases of ferns 

 borne in the same way. The weaker organization which I have 

 1871.] 



