270 Mr. Gairrrrü 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. | : 
à; The fully-developed seed is oblong, somewhat compressed, depressed on its 
HM 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 
