122 



small primitive cells, we find in several plants considerable 

 differences ; in Pinus we may still see in March and April the 

 large primitive cells separated into four distinct loculi. M. 

 Link* assigns to the tissue of these cells a peculiar name ; he 

 calls it Collenchyma, from its similarity with gluten. M. Link 

 also regards the well-known threads in the anthers of the 

 GEnothertz as remains of the membranes of the original cells. 



M. Schleiden considers the placenta to be a formation of 

 the axis, and the carpel leaves to be modified true leaves, 

 which at the commencement are separated, and only cohere 

 subsequently in various ways to form the different kinds of 

 ovaria. In the Graminece and Cyperaceae the ovarium con- 

 sists of a single leaf, in the Conifers it remains open, in the 

 Resedacece three carpel leaves are united above to form one 

 open basin ; frequently the carpel leaves are bent towards the 

 axis, and then again turned backwards. In the palms, the 

 embryo is originally, soon after the impregnation, perfectly 

 erect ; the inner side of the ovarium does not however in- 

 crease in height as the seed advances to maturity : thus the 

 apex of the embryo becomes fixed and serves as a central 

 point, about which the radicula, in the unilateral development, 

 describes a quadrant, and in this manner the embryo horizon- 

 tails lateralis originates. 



M. Schleiden commences his remarks on the ovulum and 

 placenta, with the description of the female flower of Taxus, 

 which is nothing more than the terminal bud of the collateral 

 axis ; the axis terminates in a small protuberance, which is 

 the nucleus of the ovule ; and since subsequently in the act of 

 impregnation a union of this axile formation takes place with 

 the pollen, impregnation consists in nothing more than in 

 the conjunction and balancing of the two most important an- 

 tagonistic forces the plant possesses, viz. those of the hori- 

 zontal (leaves) and of the vertical (axis) structure. 



The nucleus is the most essential part of the ovule ; its en- 

 velopes, which are termed ovular membranes, are only to be 

 considered as collateral formations, and M. Schleiden regards 

 them as amplexicaul integumental leaves, which are here com- 

 bined into a sheath-like envelope. Now the nucleus either 

 mains naked or is provided with a simple or double integu- 



* Philos. Bot. cd. alterna, ii. p. 199. 



