THE VEGETABLE CELL. Ill 



lopment of the ovule^ from the parent-plantj these envelopes to- 

 gether with the embryo, are collectively termed the &eed, and the 

 plants which bear seeds, Phanerogamia or E'inhryonatce. 



Ohserv. As will appear below, all the i>lants beaiing spores are not 

 unisexual, but the impregnation in them standb in a totally different rela- 

 tion to the production of the new plant, from what it does in the Phane- 

 rogamia. In the latter, the formation of the embiyo is the immediate 

 result of the impregnation ; when this does not take place, the seed 

 cannot germinate. In the Cryptogamia, on the contrary, which have an 

 impregnative process, neither the cell which forms the spore, nor the 

 spore itself become impregnated, but this is formed and becomes capable 

 of germination without a previous impi-egnation, and impregnating organs 

 are found, sooner or later, upon a germ-plant, or pro-emh yo, growing from 

 the spore, upon the action of which organs depends the development of 

 the yet imperfect plant mto a complete vegeta]:>le. 



a PROPAGATION BY SPOBES. 

 a. Propagation of Thallophytes. 



There is considerable variation in the modes of development of 

 the spores in the different groups of Gryptogamons plants. It 

 will not be without interest to take a brief glance at the principal 

 modifications. 



In the Fimgi we are above all struck by the production of an 

 enormous number of spores, so that in proportion to the great 

 mass formed by the spores, and in the higher Fungi in propoition 

 to the large sporangium, the vegetative part of those plants, the 

 thallus, composed of loosely-connected filaments, and in most cases 

 devoid of any definite outline, exhibits an inconsiderable deve- 

 lopment. 



In the lowest forms of Fungi, the Coniomyeeies and Syjyho" 

 Tnycetes, the formation of the spores, notwithstanding the innu- 

 merable shapes under which these plants present themselves, is 

 extremely simple, their production depending on a breaking-up 

 of the fructifying part of the Fungus into its constituent cells, or 

 into granules composed of several cells closely connected together; 

 whence L^veilld says, correctly, that the Fungus consists, in its 

 simplest form, of a simple or cellular filament terminating in a 

 spore. When we come to the Mueorinece, we already find an 

 advance, for here, as in Ascophora, the extremity of the filament 

 expands into a vesicular cell, in the cavity of which a mass of 

 spores are formed by &ee cell-formation. A similar origin of the 

 spores is met with also in the higher forms of Fungi, in which, 

 however, the single cell producing the spores no longer constitutes 

 the entire organ of fructification, but large sporangia appear 

 under the most varied forms, wherein the parent-cells of the 

 spores are collected together in a definite layer, which sometimes 

 lines the cavity of the sporangium, as in the OasUTomymtea, 



