of Vegetable Embryology. 231 



In tracing out the development of the embryo in others of 

 the Gramineae, MM. Mirbel and Spach found the phaenomena 

 presented by each species to be so closely similar^ that the em- 

 bryogeny of the Zea Mays may justly be considered as the 

 type of this process as carried on in all the Gramineae : still 

 however a few modifications of minor importance were dis- 

 closed ; thus, in the Zea Mays, the Euchlcena mexicana, the 

 Coix Lacryma, and in Tripsacum hermaphroditum the ovule 

 remains attached to the base of the cavity of the ovarium, 

 however advanced the period of development may be ; but in 

 Sorgham vulgare and Melica nutans the attachment of the 

 ovule is so displaced that this body is found fixed to that in- 

 ternal portion of the wall of the cavity of the ovary which cor- 

 responds to its anterior surface. Again, in Zea Mays, and in 

 Euchlcena mexicana, the apex of the ovule is inclined, and, as 

 it begins to approach its base, the primine completely covers 

 the secundine. About the same period those parts of the two 

 envelopes which correspond with the orifice of the ovary, 

 elongate into two empty points, of which one is inclosed 

 within the other. Lastly, the primary utricle in Euchlcena 

 differs from that of Zea and Sorgham, resembling a little 

 crooked cone, the base of which is rounded ; and the suspen- 

 sor, which in Sorgham and Zea arises from the base of the 

 utricle, and elongates itself in the direction of the axis to ar- 

 rive at the exostome, arises in this instance from the side of 

 the utricle, a little above its base ; and in elongating towards 

 the exostome it follows an oblique direction. 



On comparing the observations of Schleiden and Wydler 

 with those of Mirbel and Spach, which we have just stated in 

 detail, a striking and essential difference is clearly perceptible 

 between the conclusions to which these observations respect- 

 ively lead, at the same time that a wide distinction is indi- 

 cated between the doctrines necessarily flowing from each. 

 In instituting a comparison between the conditions of the 

 ovule and embryo during the progress of their development 

 as stated by these observers, it will be found, that the parti- 

 pouch with which it is surrounded. Hence we ohtain a proof that this or- 

 gan has nothing in common with the ligula. 



