TRANSACTIONS 



OF 



THE LINNEAN SOCIETY. 



I. On the Development of the Ovulum in Avicennia. By the late William 

 Griffith, Esq., F.L.S. 8gc. Sgc. Communicated hy R. H. Solly, Esq., 

 F.R.S., L.S. 8sc. 8sc. 



Read November 19th, 1844. 



In connexion with the development of the seed and embryo in Santalum 

 and Osyris, the following account of the development of the same parts in 

 Avicennia may not be altogether misplaced ; for the placentation is almost 

 precisely the same ; the same posterior elongation of the embryo-sac takes 

 place ; and in all the embryo is, at least when matured, external to the nu- 

 cleus or body of the ovulum. 



The ovula oi Avicennia appear to me to be nucleary: they closely resemble 

 in appearance the same bodies in Santalum, Osyris, Schcejrfia, Olax, Congea, 

 &c. (Tab. I. figs. 1,2.) 



The first change observed takes place in the central tissue of the ovulum, 

 which appears to become of a denser nature than the rest, the density gradually 

 extending to near the apex of the ovulum, in which, at a period antecedent to 

 fecundation, the ernbryo-sac will be found. This etnbryo-sac appeared in most 

 instances to be a membranous sac with an enlarged apex or head, contained 

 within the apex of the nucleus, and a subcylindrical body, extending backwards 

 a short way to the termination of the dense central tissue, into which at this 

 period a vascular fascicle is seen to be extended (Tab. I. figs. 3, 4.). 



VOL. XX. B 



