This extended treatise deals with bud-scales and the settles of subterranean parts of plants and their homologies with leaves. Speaking of the primordial leaf Glibel says, " it is divided into two parts, a stationary zone which takes no farther part in the leaf-formation and a part out of which the lamina is developed." He calls these parts respectively the leaf-base and upper-leaf and states that the petiole arises after the formation of the blade and is inserted between the two parts.
Bud-scales are regarded as modified foliage-leaves and divided into those formed from the blade (Syringa), those formed by the leaf-base ("Esculus, Prunus), and those consisting of stipules (Liriodendron, Quercus). In Prunus, etc., the formation of the bud-scales by the union of petiole and stipules is denied on the ground that the continuous separate development of the petiole and stipules can be followed.
* See also Org. Veg. 2: 213. 1827.
The scales of rhizomes are divided into those formed by a de velopment of the leaf-base (Dentaria, Chrysosplenium) and those formed by a modification of the upper-leaf (Labiatie, Onagrame).
, Co'tomb, G.—Note sur l'ochrea des PolygoM.es. Bull. Soc. Bot. Fr. 33 : 506-507, 1886.
" The ochrea of the Polygonums is a complex organ formed of two parts : one opposite the leaf, the leaf-sheath, the other in its axil and detached from the petiole. This is a " Practi cally the same conditions prevail in the Graminete as in Poly gonum with the difference that in the former the sheath proper is greatly developed and little prolonged beyond the insertion of the blade, while in the latter, the sheath proper remains short and is much prolonged above the petiole. By union with the ligule it forms an ochrea. So considered the ochrea is not peculiar to the Polygonacefe. It is found also in Ficus and Magnolia, establish ing the transition between the ochrea and stipules properly so called.
Bull. Soc. Bot. Fr. 34: 141-142. 1887.
Commenting on the preceding paper, the author says that the leaf is primitively unifasciculate. The concrescence of a verticil of elementary leaves, such as occurs in the fossil Asterophyllites, gave a sheath analogous to that of Equiseluin ; the bundle of one of these elementary leaves becoming predominant and functioning as a midvein gave rise to an aggregate leaf, the first stage of a high differentiation. In this way the origin of the leaf-blade in Polygonum, Platanus, etc. is explained, while the ochrea, the homologue of the sheath of Equisetunz, remains as a vestige of the primordial state.
The author has made investigations experimenting upon a large number of plants, by the removal of the lamina of the leaves at the earliest possible stage of development, in order to observe the effect upon the development of the stipules and so determine their physiological relation to the leaf-blade. Only in exceptional cases was the ultimate size of the stipules increased, and those where the stipules were normally foliaceous.
This paper is the result of an exhaustive anatomical study of stipules and their homologues. The results obtained are of great interest and value. They are admirably summed up at the close of the paper as follows : " When a leaf is sheathing, the sheath may be prolonged in a ligule situated above the point of insertion of the blade upon the sheath.
" In this organ three regions may be recognized : " 1. The lateral regions into which the marginal bundles of the sheath are merely prolonged. These regions naturally do not exist if all the bundles of the sheath enter into the leaf.
" 2. The stipular regions, the bundles of which arise from a doubling of the last bundle of the sheath entering into the leaf.