4 i2 NATURAL SCIENCE. Dec, 



editor, P. A. Dangeard, who claims, among other things, to have 

 put beyond doubt the existence of an intermediate tigellar region 

 distinct from both stem and root, often reaching above the cotyledons, 

 and " possessing a veritable autonomy." He also discusses the 

 varying and often large number of cotyledons in Gymnosperms, which 

 contrasts so markedly with the pair or single one found in the dicoty- 

 ledons and monocotyledons respectively. 



Thus the stone pine (Piiius pinea) has n to 13, the corsican pine 

 (P. Laricio) 8, in the scotch fir the number varies from 6 to 9, in the 

 larch there are 5, 6, or 7, in the white spruce (Picea alba) 5 to 7, and 

 so on. One theory explains the large number of cotyledons by the 

 development of new leaf-structures between the original members, 

 while another supposes the subdivision of already existing cotyledons. 



The former idea is recalled by the study of the germination of 

 the cypresses. In Cupressus Lindlcyi, for instance, the internode 

 immediately above the three cotyledons is much shortened, although 

 the following ones are well-developed. The first whorl of three 

 leaves is thus brought on a level with the cotyledons, of which the 

 seedling seems to have six, the three true cotyledons being distin- 

 guishable only by their smaller size. Similarly, Cupressus Covneyana 

 has apparently four cotyledons. It is, therefore, conceivable that 

 by a gradual approach of the origins of the seed-leaves and those 

 of the succeeding whorl a permanent increase in the number of 

 the former might be effected. Anatomy, however, does not favour 

 this view, as in the cases examined, only the vascular bundles 

 belonging to the cotyledons are inserted on those of the primary 

 root, and M. Dangeard is of opinion that the increased number 

 is due to the division of two large cotyledons, and he derives 

 the numerous cotyledons of the Abietineae from Avaucana or some 

 closely-allied ancient genus. Examination of the seedling of the 

 Chili pine or monkey-puzzle [Avaucavia imbvicata) will easily show 

 how the transformation has been produced. Each of the two 

 cotyledons has a small number of nerves which unite at the base 

 of the leaf into a single bundle ; these nerves have become independent 

 and formed as many distinct cotyledonary bundles in the axis, while the 

 limb of the two large cotyledons has split between each bundle, 

 forming as many lobes. The mode of germination thus constructed 

 recalls strikingly that characteristic of the Abietineae, and of Piuits in 

 particular. Variations occur in the genus Araucaria which favour this 

 idea ; the total number of nerves, instead of being distributed between 

 two cotyledons, may be divided among three, or sometimes four ; while, 

 on the other hand, if we examine the course of the cotyledonary 

 bundles and their relations with those of the root in a seedling of the 

 stone pine, we observe, when the number of cotyledons is odd, a fact 

 which recalls the original union of their bundles ; some namely 

 uniting with others and not being directly inserted on those of the 

 root. The author remarks that this theory is at any rate not contradicted 



