396 Farmer . — On the Morphology and 
in extension and growth on the lines already laid down in 
the bud and flower, except in so far as the cell-secretions are 
concerned. In Solarium Dulcamara the characteristic struc- 
ture is not reached until the fruit has attained to about one- 
third of its full size, and in Rubus fruticosus the peculiarities 
of the pulp do not become manifest until the time of maturity 
is approaching ; the c stone ’ of this fruit, as in others which 
possess this structure, is however formed very early, for 
reasons which will be considered later. It is not always 
possible to trace the cause of this variation, but there can be 
little doubt that it is to be sought for in the state of com- 
plexity and specialization which is finally reached, for these 
characters can have been acquired for the most part but 
comparatively recently ; and so in accordance with general 
principles, they will be proportionately late in their ap- 
pearance. 
To pass on now to the special part of this work, I propose 
in this paper to deal only with three forms, taken purposely 
from plants of common occurrence, and which will illustrate 
some of the varieties which are found in the nature and 
formation of pulp ; later on I shall have opportunity to speak 
of other anatomical and adaptive characters presented by 
numerous other forms. 
Hedera Helix . — This plant, with its inferior ovary, furnishes 
an example of a fruit whose pulp is mainly derived from the 
tissue of the carpels, for though the torus is not altogether 
without a share in its formation, it plays but a subordinate 
part in this respect, as will be evident from what follows. If the 
flower-buds be examined at a time when the inflorescence is 
just emerging from the scaly bract, it will be seen that the 
four floral whorls are already laid down, and that the carpels 
stand at a lower level than the other three whorls. This is 
due to the fact that they are formed relatively late, and that 
the external members are early raised up by a zone of growth 
which is formed below the level of their insertions. The carpels 
appear as five protuberances within these, and their growth 
subsequently keeps pace with that of the outer part of the 
