230 Mr. II. Giraud on the recent Doctrines 



extremity by a filiform tubular appendage, projecting at the 

 endostoinc, and called by Mirbel the suspensor. This last 

 organ is considered by Schleiden to be a portion of the pollen 

 tube. 



This early formation of the primary utricle, which may be 

 considered as the first outline of the embryo, has been proved 

 by Mirbel and Spaeh in a large number of the Gramineae ; — 

 in all those, in fact, which they have examined. 



Sixth Period. — Immediately after its first appearance the 

 primary utricle contains a fluid opake matter, in which how- 

 ever may be perceived an organized substance composed of 

 globules having each a small central cavity ; it is called by 

 Mirbel " Globulo-cellular cambium." This substance soon 

 transforms itself into a mass of membranous tissue, which be- 

 comes moulded to the cavity of the primary utricle and its 

 suspensor ; this last organ now sensibly elongates and en- 

 larges. (Fig. 6.) 



Seventh Period. — It now becomes evident that the primary 

 utricle, and the cellular tissue with which its cavity is filled, 

 constitute the first trace of an embryo, which now enlarges at 

 its thickest part, and elongates into a cellular lanceolate point ; 

 this is the lamina of the seminal leaf (hypoblaste, A. Richard ; 

 carnode, H. de Cassini), the inferior surface of which is in re- 

 lation with the interior of the ovule, the superior with the axis 

 of the spike ; at its base is the radicle, terminated by an empty, 

 flaccid, lacerated tube, — the last vestige of the suspensor, which 

 has gradually been absorbed. Upon the upper surface of the 

 lamina, immediately above the point at which it unites with 

 the radicle, there is formed a projection or swelling of the tis- 

 sue, which is the commencement of the plumule ; it soon ex- 

 tends itself, and becomes imbedded in a kind of hood, in the 

 cavity of which the first rudiments of the stem leaves make 

 their appearance. The edges of this little hood gradually 

 approach each other, unite, and form a kind of pouch* 

 (cotyledon, A. Richard and H. de Cassini). (Fig. 7. and 8.) 



* Schleiden has of late imagined that this pouch represents the ligule of 

 the cotyledon leaf; — an hypothesis which, though at first sight very attract- 

 ive, loses all its probability as soon as germination commences ; for then 

 the pedicel, which always takes its origin above the point of the attachment 

 of the cotyledon leaf, is seen to elongate, and to bear up with it the little 



