395 
Physiology of Pulpy Fruits. 
pulp is purely physiological, and hence more than one mor- 
phological member may be expected to be called into 
requisition to furnish it, just as the physiological organs of 
attachment and absorption may be represented by members 
other than roots in the true morphological sense of the 
word ; and just as in the latter case, an accurate perception 
of the morphological nature of the organ which happens 
to function as a root-like body is indispensable, from a 
scientific and philosophical standpoint, to the formation of 
a correct appreciation of the body in question, so also 
in the case of the class of fruits under discussion : it is 
impossible that they can be properly understood unless 
the real nature of the pulp-forming tissue is clearly ap- 
prehended. 
Besides the extreme case of the Honeysuckle, already 
mentioned, and the more common forms of berries and 
drupes, there are some plants, as the Rose and Strawberry, 
where the entire pulp is derived from the torus ; in others the 
floral envelopes contribute the chief portion, as in Hippophae 
and Morus . In Citrus again it owes its presence to hairs 
which spring into the ovarian cavities, and which become 
distended with liquid. Another, and more irregular source 
of pulp is found in the aril, which makes its appearance 
after fertilization in some fruits : an example of this class 
is afforded by Taxus 1 . Even in berries the relative parts 
played by the placenta and the pericarp show great variety 
in different plants. Thus in Vitis each furnishes about half, 
in Solarium Dulcamara the placenta, and in L igu strum vulgar e 
the pericarp, provides almost the whole pulp. 
It is a point of some interest that considerable difference 
prevails amongst plants as to the time at which the characters 
which distinguish the mature fruit first come into prominence. 
Thus in Hedera Helix the main features are all apparent 
before the flower is over, subsequent changes consisting chiefly 
1 There is perhaps some doubt as to whether the structure commonly known as 
the aril in this plant should be really included under this name ; but I have followed 
the ordinary usage as regards this case. 
