Fecundation in Orcltidece and Asclepiadea. 709 



opake speck is the commencement of the future embryo. At 

 this period, or until the opake corpuscle or nucleus has acquired 

 more than half the size it attains in the ripe seed, a thread may 

 be traced from its apex very nearly to the open end of the testa, 

 or as it may be supposed, to the apex of the original nucleus of 

 the unimpregnated ovulum. 



This thread consists of a simple series of short cells, in one of 

 which, in a single instance onlj;" however, I observed a circu- 

 lation of very minute granular matter ; and in several cases 

 I have been able to distinguish in these cells that granular 

 areola so frequently existing in the cells of Orchideous plants, 

 and to which I shall have occasion hereafter to advert. 



The lowermost joint or cell of this thread is probably the 

 original state of what afterwards, from enlargement and depo- 

 sition of granular matter, becomes the opake speck or rudiment 

 of the future embryo. :•; 



The only appreciable changes taking place in this opake 

 rudiment of the embryo are its gradual increase in size, and at 

 lenoth its manifest cellular structure. 



In the ripe state it forms an ovate or nearly spherical body, 

 consisting, as far as I have been able to ascertain, of a uniform 

 cellular tissue covered by a very thin membrane, the base of 

 which does not exhibit any indication of original attachment at 

 that point ; while at the apex the remains of the lower shrivelled 

 joints of the cellular thread are still frequently visible. 



This cellular body may be supposed to constitute the Embryo, 

 which would therefore be without albumen, and whose germi- 

 nating point, judging from analogy, would be its apex, or that 

 extremity where the cellular thread is found ; and consequently 

 that corresponding with the apex of the nucleus in the unim- 

 pregnated ovulum. 



The description here given of the undivided embryo in Orchi- 

 deous 



