NATURAL SCIENCES OF PHILADELPHIA. 123 



Pine needles are not properly leaves, but rather branchlets, which, 

 through the real leaves becoming attached for nearly their whole 

 length to the axis or stem, had of necessity taken on themselves 

 the offices of leaves. He believed that many botanists had coin- 

 cided with his views ; but some very distinguished ones, among 

 others he believed his esteemed friend Prof. Asa Gray, did not feel 

 warranted in fully agreeing with him. He was rather glad of this 

 hesitation, because it was an incentive to him to continue his 

 observations and searches for new facts which might either 

 weaken or confirm his original views. 



He now wished to offer to the Academy two additional obser- 

 vations in favor of the axial origin of these so-called leaves. 



In plants in general the leaves unfolded contemporaneously 

 with the branches or axes. He could not call to mind an instance 

 where the axis first extended to its full length before the leaves 

 ventured to push forth from the nodes. The axial buds usually 

 remained dormant until this final length was approached. When 

 this occurred, or if anything happened to destroy the apex of the 

 growing shoot, then the axial buds pushed into growth, and never 

 to any great extent before. In the Pine family we had the follow- 

 ing axial experience. The buds which bore the needles were axial 

 buds, situated at the base of the scale the adnated leaf as he 

 maintained. These buds remained nearly at rest until the axis 

 had reached its full length, and in this respect coincided with the 

 axial buds of trees in general. A pine tree in the spring season 

 presented the appearance of an immense ehandelier, with its long 

 axial shoots as the naked burners. In this respect it is apparent 

 that, regarding the fascicles of pine needles as branchlets, the 

 law of folial development coincidental with axial growth finds no 

 exception in the Pine family. 



The next striking consideration was one derived from the 

 nature of the inflorescence. In vegetable morphology, the floral 

 system of plants was made up of neither leaf nor axis separately,, 

 but conjointly of both. In the inflorescence of the pine, the male 

 catkins each took the place of a fascicle. The axial bud at the 

 base of the leaf scale, instead of a bunch of needles, developed as 

 a spike of flowers. This spike or catkin is metamorphosed nee- 

 dles. If these needles were leaves merely, we could hardly ex- 

 pect inflorescence to be formed from them. It would be an excep- 

 tion to regular rule. But regarding the needles of the pine as 

 rather axis than leaf, their development to flowers accords with 

 general law ; and he held that it was more philosophical to accept 

 conclusions based on a;eneral law. than to hunt for new laws to 

 account for apparent exceptions to general rule. 



For his own part he felt there needed no further reasoning than 

 he had offered at previous times ; but he thought perhaps these 

 additional suggestions might have weight witli other minds that 

 had not yet decided as fully as he had done. 



