of Vegetable Embryology. 229 



now changed its position ; its axis was at first parallel with 

 that of the spike ; but it is now inclined at an angle of about 

 45°. The secundine is still in advance of the primine. 



Fourth Period. — The ovary is now of a rounded form, ha- 

 ving its orifice narrowed into a kind of canal. The style con- 

 tinues to enlarge, and has its upper extremity terminated by 

 two dentitions, more or less distinct, which may be considered 

 as constituting a double stigma. The axis of the ovule now 

 makes an angle of 90° or 100° with that of the ovarium, but 

 coincides with that of the nucleus, at the apex of which it 

 terminates. Very near this point, in the interior of the nu- 

 cleus, there appears a small ovoid cavity, which contains a 

 transparent mucous matter, first pointed out by Schleiden. 

 (Fig. Ad.) In the same ratio as the axis of the ovule in- 

 clines from that of the spike, do these portions of the pri- 

 mine and secundine, which lie on the opposite side, increase 

 in size and elongate ; while those portions which are attached 

 to the side next the axis of the spike remain almost stationary 

 in their development : from both these envelopes a process 

 extends into the canal leading from the ovarium. 



Fifth Period. — The ovarium continues to enlarge and the 

 style to elongate ; in the latter may be observed, as Brongniart 

 first noticed, two bundles of tubes, which, after running to- 

 gether for a short distance, divide and pass off to each side of 

 the ovarium, and continuing in a parallel direction, are ulti- 

 mately lost in the dentiform projections which constitute the 

 stigma. At this period the ovule is inclined at an angle of from 

 125° to 135°. The mucilage of the little cavity situated at the 

 apex of the nucleus disappears ; and at the same point may 

 be distinctly seen a large ovoid, diaphanous utricle, which 

 fills and lines the cavity. (Fig. 5 a.) This utricle is called 

 by Mirbel the primary utricle. The fact of such an organ 

 being formed, and of its having acquired a sensible progress 

 in growth, before the period of impregnation, is of the great- 

 est importance with reference to the views of Schleiden ; this 

 utricle is what is described by that observer as " l'extremite 

 anterieure du boyau pollenique." It is surrounded by a thin 

 projection, upon which are attached small spiral vesicles, ar- 

 ranged in close clusters ; and it is terminated at its inferior 



