AN OLD-WORLD BOTANIST 
225 
my intention is simply to summarise briefly the account which 
our author gives of the sap of plants, a subject to which he 
devotes six of his folio pages. 
He commences by noting the usual arguments for the circula- 
tion of the sap, such as that, by ligaturing the stem, the part 
above is found to swell considerably ; and in this connection 
it must be remembered that the botanists of that age were 
handicapped by the notion that, even in detail, the organisation 
of the plant must be similar to that of the animal, both morpho- 
logically and physiologically. After noticing “ the excellent 
Bobart’s ” contention that plantscontain two juices, one imbibed 
by the roots, and one by the extremities of the branches from 
the air, our author proceeds to define the sap as a juice 
“ furnished by the earth and changed into the plant,’’ and 
remarks that this juice, “when it enters the roots — the bark 
whereof is furnished with excretory vessels fitted to discharge 
the excrementitious parts — is earthy, watery, poor, acid, and 
scarcely oleaginous at all.” I have italicised this word acid, 
since I shall have occasion to comment thereon anon. In a very 
curious paragraph, on the ascent of the sap and its continual 
modification en route, he traces it through the flower (to whose 
petals he erroneously ascribes a digestion and alteration of the 
sap) to the stamens; “these communicate it to the dust in the 
apices which is, as it were, the male seed of the plant, where, 
having undergone a farther maturation, it is shed into the pistil, 
which performs the office of an uterus ; and thus having acquired 
its last perfection it gives rise to a new plant.” It would appear 
doubtful from this whether our author recognised the existence 
of any female element at all, although he recognises both male 
and female organs ; but one can hardly wonder at such omission, 
considering at how comparatively recent a period the true 
process of fertilisation in even animals has been understood. 
Still to us it sounds sufficiently strange to find the “ sap,” 
transformed into pollen and then into embryo, and never a 
suspicion of any such factor as protoplasm ! We are next told 
that “ the motion of the juices in vegetables is produced, much 
like that of the blood in animals, by the action of the air,” — a 
discovery referred to the “ admirable Malpighi : ” for it seems 
that there are two orders of vessels in plants (1) such as convey 
the juices, and (2) air-vessels within which air is continually 
inspired and expired ; and it is explained that by the expansion 
and contraction of these vessels, according to temperature, the 
juices in the other vessels are set in motion. Readers will 
do well to compare with this interpretation the modern theories 
of the effects of root-pressure, and of transpiration, upon the 
ascent of the sap.* Miller then traces the sap up to the 
branches, and asserts that, “ having everywhere deposited some- 
* See Vines’ “ Physiology of Plants,” and F. Darwin’s British Association 
address as reported in Nature, vol. lvi., p. 367 et seg. 
