NATURAL SCIENCES OF PHILADELPHIA. 401 



but it was also interesting from its bearing on a physiological 

 question of importance. The first suggestion made by most of 

 his botanical friends, to whom he had mentioned these facts, and 

 he believed the first that would occur to the minds of most bota- 

 nists, would be that these extra strong spines would be found in 

 connection with extra strong shoots. If these were true spines 

 that is to say, abortive branches the inference would be a fair 

 one ; but these thorns were the analogues of stipules, as we look 

 for in allied leguminous plants, and would, therefore, be most 

 likely to follow the laws which influenced stipular productions. 

 One of those laws was, at least so far as his own observation 

 went, that stipular development was in inverse ratio to ordinary 

 growth force. For instance, we say that the scales which cover 

 the buds of trees in winter are metamorphosed leaves ; but this is, 

 in many cases, certainly not strictly true. Bud scales are, in 

 many cases, but modified stipules where leaves have these appen- 

 dages, and dilated petioles where they have not. This peculiar 

 development of the stipules, of course, only commences with the 

 decline of growth force in the axis in the fall, or before it has 

 achieved great power in the spring. 



The specimens of Robinia exhibited illustrated the same law. 

 In the one from Detroit the three-quarter inch slender stipular 

 spines it would be seen by the members, were not from a very 

 vigorous branch, but from a very slender one; but the best illus- 

 tration was on the strong branch which he exhibited, cut to-day, 

 and with the inch spines before referred to. This was from the 

 upper portion of a branch of this year's growth, 6 feet long. On 

 the lower portion of the part exhibited, produced when the growth 

 force would be at its maximum, the spines are of the normal size, 

 about one-quarter of an inch in length ; and these spines increase 

 in length gradually to an inch in proportion as the season's growth 

 becomes weaker. But there is a still stronger illustration in the 

 secondary branchlets which have grown from the main one. These 

 are no thicker than straws, but the. spines are about three-quarters 

 of an inch in length, and slender, and much larger, in comparison 

 with the axis to which they are attached, than the largest on the 

 strong main branch. 



On the Anatomy of the Giraffe. Dr. H. C. Chapman remarked 

 that, although the anatomy of the giraffe has been well described in 

 the Phil. Trans, by Prof. Owen, as the opportunity of dissecting 

 it does not occur often, and the literature of the subject is not 

 very full, it does not appear superfluous to call attention to one or 

 two facts noticed in a dissection of the male animal that died some 

 time since in the Zoological Garden, and whose stuffed skin makes 

 a valuable addition in our museum. He had pleasure in saying 

 that he found the internal organs as described by Prof. Owen, 

 save in reference to the manner in which the great bloodvessels 



