THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, October 4, 1859. 
7 
as hardy as our common Scabious. Although they are mostly 
natives of Europe, yet they are little known, certainly not so well 
as they deserve. They require a deep loam and full exposure. 
Propagated by seeds chiefly, and also by cuttings made of the 
short shoots near the stem. Sow the seeds in March, in a bed of 
sandy loam, in an open part of the garden. Transplant when 
very young, as the roots are not very fibrous, being apt to run 
straight down into the soil. Plant them singly afterwards where 
they are to bloom. They last many years without renewal, but 
require a mulching of manure every autumn. 
By Cuttings .—When seed cannot be procured and it is desired 
to increase the plants of any of the species, then in the spring 
take off the offsets close to the stem, and plant them in sand 
under a hand-light in a shady place. They will root, though but 
slowly; and when roots are emitted take them up directly, and 
plant them in their final destination in fresh soil at once. All are 
worthy of cultivation, but more especially the dwarf-growing 
kinds. f rr j , .■ j \ T. Appleby. 
(To be continued.) 
Death op Dr. Ntjttall. —We have to record the death, on 
the 10th inst., of Dr. Thomas Nuttall, at his residence, Nut- 
grove, St. Helens, Lancashire, at the age of seventy-three. He 
was born in Yorkshire, brought up a printer, and emigrated 
to the United States in the latter part of the last century. He 
devoted his leisure time to the study of botany and geology, 
published the ‘ Genera of North American Plants,’ ‘ The Birds 
of the United States,’ and other works. He travelled in Cali¬ 
fornia, and published several papers on the shells and plants of 
that region. Dr. Nuttall returned to England, living at Nutgrove, 
an estate which was left to him on condition that he should reside 
on it.—( Athenaeum .) 
THE SCIENCE OE GARDENING. 
(Continued from 'page 385, Vol. XXII.) 
The transpiration from the leaves of plants is effected through 
pores, or stomates, varying in number and size in every species, 
but being, usually, either largest or most numerous in plants 
inhabiting moist or shady localities. This is a wise provision; 
for such plants, consequently, have an abundant supply of moist 
food to their roots, requiring a competent provision for its elabo¬ 
ration and reduction from superfluous water. Those plants 
which are natives of sandy, exposed soils, have, on the other 
hand, either fewer or smaller stomates. Crinum amabile, an 
inhabitant of swamps near Calcutta, has 40,000 of the largest 
known stomates on every square inch of its leaves ; whilst an 
Aloe from the exposed sands of the Cape of Good Hope has 
45,000 of the smallest, and not equal in transpiring power to 
half the same number of stomates in the leaves of the Crinum. 
We have not been able to test their relative transpiring powers ; 
but of two similarly constructed plants, of nearly similar size, 
the rate of perspiring in July, both in a temperature of 65°, 
but not exposed to the sunshine, was as follows. In six hours 
Mesembryanthemum deltoides, native of a dry soil, exhaled eight 
grains, while Caltlia palusiris, found only in marshy places, 
exhaled twenty-five grains. In the absence of certain inform¬ 
ation, therefore, the gardener may conclude, as a guide for his 
treatment of a new plant, that, if its stomates are large, it will 
require abundance of water. 
The stomates present themselves under the form of oval pores, 
sometimes almost round, at others rather elongated. They are 
usually open in leaves which grow well, and in parts exposed to 
the sun j they are less open, or sometimes entirely closed, on the 
surfaces of leaves which are very old, or which have not been 
exposed to the light for some time. Their border has the 
appearance of a kind of oval sphincter, capable of being opened 
and closed. The line which surrounds this sphincter is always 
continuous with those which form the network of the cuticle. 
Under this, and in the interval between the border of the 
sphincter and the pore, granules of a green matter are very 
frequently found. 
Stomates exist in a more or less distinct manner in all the 
foliaceous surfaces of vascular plants—viz., in leaves properly 
so called, in stipules, in the green bark, in the calyx, and in 
pericarps which are not fleshy; they are wanting in all buds, 
aged stems, petioles which are not foliaceous, most petals, fleshy 
fruits, and all seeds of vascular plants; they are also absent in 
all the organs of cellular plants. 
The stomates are absent in several plants, on account, it seems 
of their manner of living. t Thus—1st, They are not found either 
on the leaves or stems of plants which grow under water, such as 
Zostera, Ceratopliyllum, &c.; and in those which have part of 
their organs under and part above water, as several species of 
Potamogeton, Myriophyllum, Nymphsea, &c., the stomates exist 
only m the parts exposed to the air; they are found on the 
leaves of Ranunculus aquatilis when they are raised above the 
water, but are wanting when they grow under it. 2ndly, The 
part of the leaves of bulbous plants, which is concealed in the 
Onion, and consequently blanched, is either entirely deprived of 
them, or presents some closed and imperfect ones.. All truly 
parasitical vascular plants which are not of a green colour have 
no stomates either on their stems, or on the imperfect rudiments 
of then’ scale-like leaves, such as Orobanche, Lathrsea, Mono- 
tropa, Cuscuta, &c.; on the contrary, those which are green, 
as the Mistletoe ( Viscus ), and Loranthus, are abundantly sup¬ 
plied with them.— (Re Candolle's Vegetable Organography .) 
We have hitherto only considered the perspiration which 
passes from leaves imperceptibly in the state of vapour; but 
there are other kinds thus particularised by Mr. Keith :—“ It 
is very generally to be met with in the course of the summer 
on the leaves of the Maple, Poplar, and Limo tree; but par¬ 
ticularly on the surface exposed to the sun, which it sometimes 
wholly covers. Its physical as well as chemical qualities are very 
different in different species of plants ; so that it is not always 
merely an exudation of sap, but of sap in a high state of eleboration, 
or mingled with the peculiar juices or secretions of the plant. 
“ Sometimes it is a clear and watery fluid conglomerating into 
large drops, such as are said to have been observed by Mr. 
Millar, of Chelsea, exuding from the leaves of the Musa arbor , or 
Plaintain tree; and such as are sometimes to be seen in hot and 
calm weather exuding from the leaves of the Poplar, or Willow, 
and trickling down in such abundance as to resemble a slight 
shower. This phenomenon w r as observed by Dr. Smith under a 
grove of Willows in Italy, and is said to occur sometimes even in 
England. Sometimes it is glutinous, as on the leaf of the 
Lime tree ; sometimes it is waxy, as on the leaves of Rosemary; 
sometimes it is saccharine, as on the Orange leaf, according to 
the account of M. de la Hire, as related by Du Hamel, who, 
having observed under some Orange trees a saccharine substance 
somewhat resembling Manna, found upon further investigation 
that it had fallen from the leaves. Sometimes it is resinous, 
as on the leaves of the Cistus creticus, from which the resin 
known by the name of Labdanum is obtained, by means of 
beating it gently with leathern thongs, to which the exudation 
adheres; as also on the leaves of the Populus dilatata , or 
Lombardy Poplar, the exudation from which Ovid in his 
metamorphosing flights regards as the tears of Phaeton’s sisters, 
whom he transforms, a3 it is supposed, into this species of 
Poplar. Their tears were now gum. The leaves of Eraxinella, 
or Dictamnus albus, are also said to be often covered with a 
sort of resinous substance. And after a hot day, if the air is 
calm, the plant is even found to be surrounded with a resinous 
atmosphere, which may be set on fire by the application of the 
flame of a candle. 
“The cause of this excess of perspiration has not yet been 
altogether satisfactorily ascertained ; though it seems to be 
merely an effort and institution of Nature to throw off all such 
redundant juices as may have been absorbed, or secretions as 
may have been formed, beyond what are necessary to the due 
nourishment or composition of the plant, or beyond what the 
plant is capable of assimilating at the time. Hence the watery 
exudation is perhaps more than a redundancy of the fluid 
thrown off by imperceptible perspiration, and the waxy and 
resinous exudations nothing more than a redundancy of secreted 
juices; all which may be still perfectly consistent with a healthy 
state of the plant.” 
The circumstance most influential in controlling tire transpira¬ 
tion of plants is the liygrometric state of the atmosphere in which 
they are growing. The drier the ah’, the greater is the amount 
of moisture transpired; and this becomes so excessive, if it be also 
promoted by a high temperature, that plants in hothouses where 
it has occurred often dry up as if burned. Mr. Daniell has well 
illustrated this by showing, that if the temperature of a hothouse 
be raised only five degrees, viz., from 75° to 80°, whilst the air 
within it retains the same degree of moisture, a plant that, in 
the lower temperature exhaled fifty-seven grains of moisture , 
would, in the higher temperature, exhale 120 grains in the same 
space of time. 
