401 
Physiology of Pulpy Fruits. 
to any great distance, as the increasing pressure they would 
necessarily encounter would certainly prove a serious check 
to their progress. Still the fact of their occurrence is not 
without interest in connection with the so-called pseudo- 
parenchyma of fungi, and other tissues of a similar nature. 
At the period when the pedicels of the separate flowers 
begin to lengthen, the compact mass of tissue of which the 
carpels are composed suffers a change in appearance, due to 
the extensive formation of intercellular spaces. Of course the 
carpels are not composed exclusively of parenchyma, for 
besides the vascular bundles, there are numerous secretion 
passages present which are similar to those found in the rest 
of the plant ; since, however, their presence does not materially 
influence or contribute to the pulp they may be dismissed from 
further consideration. I have already mentioned the regu- 
larity which characterises the cell-divisions taking place in the 
peripheral layers or rind of the fruit ; and it may be regarded 
as certain that to the rapid radial division, and consequent 
tangential extension, of this rind is due the early splitting 
apart of the internal cells of the young ovary. Certainly the 
cells referred to are subjected to a strain tending to make them 
occupy a larger space than they normally would do, for besides 
the fact that cell-multiplication is not very active as yet in this 
region, growth in size is also very limited, and yet the ovary 
as a whole is increasing very largely in bulk. The cellular 
tissue splits up, then, to allow of this increase, but it is rather 
a passive, than an active process like that in Crataegus , and 
the cell-walls are still very thin, no clear middle lamella being 
visible until specially looked for, nor have I as yet succeeded 
in tracing any connection between the splitting and a degenera- 
tion of the cell-wall in this inner mass of cells. But the walls are 
so exceedingly thin that it might easily escape even careful 
observation, and the formation of mucilage already hinted at, 
and which will shortly be described, renders it quite probable 
that such a connection does exist. The cells which eventually 
separate do not however become completely isolated, but re- 
main united with each other by their ends, so as to form 
