192 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Structure and Development. 

 Vegetative. 



Anatomy of Seedlings of Labiatse.* — R. Yiguier, who has investi- 

 gated the structure of the seedlings of Lamium album and other 

 members of the order, describes the following general results. The 

 stem structure is independent of that of the hypocotyl, and there is 

 properly speaking no transition from root to stem. The cotyledons in 

 Lamium album and other Labiates such as Leonurus Cardiaca, Nepeta 

 Cataria, Hyssopus officinalis, etc., show very plainly an alternate arrange- 

 ment of the phloem and sylem bundles. The adventitious roots 

 originating below the cotyledons are two in number, and arise in a 

 plane perpendicular to that of the primary wood bundles of the 

 hypocotyl. 



Adventitious Endogenous Buds.| — C. de Candolle has studied the 

 morphology of the adventitious buds arising on the trunk and branches 

 of trees and shrubs. These are always endogenous, arising in the tissue 

 round about the cambium. The actual layer from which they take 

 origin has not been precisely determined except in a few dicotyledons, 

 where it is the pericycle, but the origin is probably the same in other 

 plants of the same class. The shoots formed by these buds always 

 show at first the vegetative characters of the seedling of the same 

 species. They are never exactly like the axillary shoots of the same 

 tree, and sometimes differ from them in a striking manner. They 

 repeat the course of evolution of the leaf on the plant, if we except the 

 cotyledons ; that is to say, where the form characteristic of the adult is 

 only gradually assumed in the development from the seedling, the 

 juvenile stages are reproduced in the development of the adventitious 

 shoot. 



The author discusses in detail the various species which he studied ; 

 they include Eucalyptus globulus, the Walnut, Oak, Ivy, Hornbeam, 

 and Horse-chestnut. In every case the buds are clothed with scales 

 on their appearance, and this would seem to be a general character of 

 endogenous buds, occurring even in species such as those of Pterocarya, 

 where the axillary buds have no scales, and also where, as in the Chestnut, 

 the seedling does not bear basilar scales. Phyllomes resembling the 

 cotyledons are never found at the base of the adventitious shoot ; these 

 seem peculiar to the embryo, and the adventitious shoots reproduce only 

 those phases of individual evolution which are subsequent to the coty- 

 ledons. In this respect they are intermediate between the embryos 



* Comptes llendus, cxxxvii. (1903) pp. 804-5. 

 t Arch. Sci. Phys. et Nat., xvi. (1902) pp. 50-70. 



