270 Mr. Griffith on the Ambrosinia ciliata of Roxburgh. 



from the centre or disc of the areola. The obliquity of the conical apex is 

 now considerable. The chief bulk and inclosed part of the embryo occupies 

 at this period about the upper two-thirds of the excavation, but does not as yet 

 extend into its lower globular portion. 



As the development proceeds, the testa becomes more enlarged and more 

 cellular, and the originally conspicuous foramen becomes more indistinct. The 

 nucleus becomes more dense and callous, and its globular base as well as the 

 cavity become more enlarged, and hence the more apparent constriction of 

 its neck. The embryo as it enlarges extends downwards into the globular 

 portion of the cavity of the nucleus, which it subsequently fills entirely. The 

 sacciform cellular tissue previously noticed is pushed further down into the 

 excavation as this downward growth of the embryo advances, and subse- 

 quently it forms a thin lining interposed between the globular base of the 

 embryo and the corresponding wall of the cavity of the nucleus. The upper 

 cylindrical portion of the inclosed part of the embryo becomes, if possible, 

 more firmly embraced by the neck of the nucleus. 



The exserted portion soon ceases to elongate, but increases much trans- 

 versely. The rudimentary processes of the plumula become more and more 

 elongated, and the extent of surface from which they are produced more and 

 more increased. They are developed from within outwards, and subsequently 

 become so numerous as to occupy the chief part of the periphery of the ex- 

 serted and much-enlarged portion. Their growth is very rapid, and does not 

 correspond with that of the testa, which becomes more and more thin and 

 membranous as the processes increase in size. Owing to their greater ratio 

 of growth, these processes subsequently become recurved towards their apices. 

 This curvature will however be seen to commence before the processes have 

 equalled the testa in length. The radicle keeps up a very slight correspond- 

 ing ratio of growth, but its obliquity becomes increased. It always remains 

 conical, and as from its direction it soon comes into contact with the lax, 

 cellular, basilar portion of the testa, it becomes imbedded in it, and ends by 

 perforating it altogether. 



The fully-developed seed is oblong, somewhat compressed, depressed on its 

 inner, convex on its outer surface, constricted towards the hilum ; this portion 

 being of a brownish tint and hard to the touch. The testa closely embraces 



