266 Linnean Society. [Nov. 4, 



embraced by the neck of the nucleus, the tissue of which has become 

 more and more callous or indurated. Still later the testa becomes 

 more enlarged and cellular, and its foramen more indistinct ; the 

 nucleus is denser and more cellular, and the embryo extends down- 

 wards into the globular portion of its cavity, displacing the sacci- 

 form cellular tissue with which it was previously filled. The ex- 

 serted portion of the embryo now ceases to elongate, but increases 

 greatly in a transverse direction ; the area on which the processes 

 of the plumula ar# developed is much enlarged, they become more 

 numerous and elongate rapidly, and, as the testa does not increase 

 with equal rapidity, their apices become recurved. The radicle in- 

 creases much less rapidly, but becomes gradually more and more ob- 

 lique, and is soon imbedded in the lax testa, which it finally perfo- 

 rates. 



The fully-developed seed is oblong, somewhat compressed, de- 

 pressed on its inner, convex on its outer surface, and constricted 

 towards the hilum, where it is of a brownish tint and hard to the 

 touch. The testa closely embraces the plumula ; it is cellular to- 

 wards its base and where it surrounds the dense internal globular 

 body, membranous throughout the rest of its extent, and so thin 

 that the processes of the plumula are visible through it and give it a 

 greenish tint. The descending portion of the embrj'o, which con- 

 stitutes the cotyledon, is clavate and nearly enclosed within the dense 

 indurated nucleus, the enclosed part separating with the nucleus with 

 great readiness, and about the time of the dehiscence of the fruit 

 spontaneously. The exserted portion of the embryo consists, ex- 

 clusively of the base of the cotyledon, of a fleshy plano-convex body, 

 the plane surface of which is depressed towards the centre, where 

 the cotyledon is attached, and gives origin on one side to the conical 

 and acute radicle, which is always directed away from the placenta. 

 The circumference of the convex surface is entirely occupied by the 

 processes which constitute the plumula, and the outermost of which 

 are about an inch in length. These processes are furnished with 

 vessels, but their chief bulk is cellular, and they are (with the ex- 

 ception perhaps of the outermost) furnished with stomata. After 

 the spontaneous separation of the enclosed portion of the cotyledon, 

 the testa is frequently found ruptured, but Mr. Griffith does not con- 

 cur with Roxburgh in regarding this as the stage of germination, 

 which he thinks cannot be said to take place until the radicle has 

 elongated and the innermost of the plumulary processes become ex- 

 panded. The axis contains the rudiments of additional radicles, 

 which after germination become exserted. 



