184 Botanical Collections. 



points out the summit of the primine, and also of the ovule, according to 

 their view of the subject. The secundine sac is totally deprived of vessels, 

 and is formed entirely of cellular tissue. It adheres by its base to the 

 chalaza, and has at its summit an opening corresponding to that of the 

 primine, and w^hich Mirbel calls the endostome. The third envelope, 

 termed by him the tercine, (the nucleus of Brown,) has no visible opening, 

 and is fixed to the bottom of the secundine : this, in its turn, includes a 

 fourth, or the quartine, apparently attached to the summit of the cavity, and 

 the quartine contains the quintine, or embryonic sac, which adheres both to 

 its apex and its base. In the upper part of the quintine, the embryo appears. 

 These different parts do not exist, or, at least, have not been seen, in every 

 ovule ; and in those in which they have been observed, they are not all 

 visible at one time, but one after the other : when the first are most 

 evident, the last are merely rudimentary, and when the latter are developed, 

 the other have often become undistinguishable. 



It results from the observations of Mirbel, that this series of developments 

 presents five distinct periods. In the first, the ovulum is scarcely per- 

 ceptible, being a small, pulpy, conical substance, without a foramen. In 

 the second, the exostome and endostome open ; and they are to be perceived 

 dilating insensibly, until they have attained their maximum. The primine 

 and secundine are manifest at this period, as is also the tercine, but this only 

 puts on the appearance of a round, or conical, cellular mass, of which the 

 apex protrudes beyond the secundine. In the third period, the primine and 

 secundine, united together, increase much in size, have their double orifice 

 closed, and, consequently, conceal the tercine, which becomes a membranous 

 bag. In the fourth period, the quartine arises from the internal surface of the 

 nucleus ; and the quintine is elongated into a narrow utricle, attached by the 

 one extremity to the point corresponding to the chalaza, and by the other to 

 that near to the endostome. This is the period in which the ovule passes 

 into the state of a seed. In the fifth period, the quintine expands, — the 

 embryo develops the cotyledons as well as the radicle, and reaches its full 

 size, — and the substance of the perisperm is formed either in the cells of the 

 quintine, or in those of the quartine or tercine, when it is no longer possible 

 to recognize the different envelopes of the ovule, and it becomes necessary 

 to designate the parts of the seed by names different from those employed 

 in the ovule. 



With regard to the changes of form and position that the ovule undergoes 

 in these different periods, Mirbel applies the term, statics of development, to 

 the force of expansion, or of inertness or contraction of the different parts ; 

 and he endeavours to shew how, in the ovule, these causes, acting, sometimes 

 together, sometimes independently, alter or preserve the regularity of the 

 primitive shape. Every ovule, according to him, has at first a regular form, 

 so that, if the development be equal in all points, its regularity must be 

 preserved ; but, if the force of development be greater on one side than on 

 the other, an irregularity must ensue. An equilibrium of forces must thus 

 have taken place in an orthotropous seed, but not in the anatropous, or 

 campulitropous seeds. When an ovule tends to be anatropous, the chalaza, 

 or the inner extremity of the funiculus, is pushed forward in a slightly 

 oblique direction, and inverts the column, so that its base now occupies the 

 place where its summit was, and vice versa. This kind of resupination takes 

 place in a very short space of time ; and, by a series of observations, M. 

 Mirbel has been able to trace its progress. As the chalaza is merely the end 

 of the funiculus, the inversion cannot take place without an elongation of the 

 funiculus, equal at least to the length of the axis of the ovule. Also, in the 

 anatropous seeds, a portion of the funiculus, (that portion which botanists 

 term the raphe,) united laterally to the primine, extends from the exostome 

 to the chalaza. Three characters distinguish every ovulum destined to 

 become in maturity a campulitropous seed, viz. 1. The indissoluble union 



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