September 23, 1880. ] JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 28B 
as the negative pole of the battery. Of the positive metals zinc 
is chiefly, and iron occasionally, employed ; and of the negatives, 
copper, carbon, platinum, gold, and silver are the most important, 
the three first being most commonly used. In a galvanic battery 
thus composed the comparative quantity of electricity produced, 
provided the metals be the same in each case, will be in proportion to 
the size of the plates, but the intensity is in proportion to the num¬ 
ber of pairs employed. A battery of a single pair of plates has but 
little chemical influence, and to effectually decompose chemical 
compounds it is necessary to increase the intensity of the elec¬ 
tricity. The bearing’of these facts upon Mr. Bridgman’s statement 
concerning the Fern case are as follows : The metals of which it 
was composed—viz., zinc and iron, were similar in galvanic con¬ 
stitution, and therefore would under any circumstances produce a 
very small quantity of electricity, which would in that particular 
instance be still more reduced by the smallness of the surfaces in 
contact, for the edges could not exceed an inch or two in diameter. 
The amount of electricity evolved, presuming there to be any 
action at all, would therefore be so very small that it is highly 
improbable it could affect growing plants either injuriously or 
otherwise. I should be inclined to attribute the damping of the 
Ferns either to insufficient ventilation or to some obnoxious 
material having been employed in painting the inside of the case. 
As to the effect of placing strips of wood between the upper and 
lower portions of the case, let me ask, Were they placed all round 
so as to render the case as close as it was previously, or only at 
the ends or sides ? If the latter, then the increased amount of air 
admitted would effectually dissipate the mildew. Finally, what 
soil was employed ? This may have had some influence in the 
matter. 
Mr. Bridgman’s observations concerning manures are also, to 
say the least, unique. Manures are, he remarks, divisible into two 
classes—those containing oxygen and those devoid of that element ; 
the former conveying “ oxygenated food ” to the plant through its 
roots, and the latter “producing mildew and other fungi.” From 
this it appears that Mr. Bridgman regards oxygen as the chief food 
of plants, and those compounds that do not contain it as positively 
injurious. This requires some proof ; for why is ammonia, con¬ 
sisting of nitrogen and hydrogen only, so beneficial to plants 1 Is 
it not because both the elements are of considerable importance 
to their health and are readily assimilated ? Nitrogen especially 
is necessary to the sustenance of the living portion of the plant— 
the protoplasm, and the chief sources are nitric acid and ammonia ; 
the former contains a portion of oxygen, and the latter none. 
Further, if these non-oxygenated compounds are so injurious to 
vegetation as your correspondent would have us believe, why are 
they beneficial to fungi, which are to a large extent of similar 
chemical composition to other plants ? 
Concerning the injurious effects of excessive applications of 
manure there can be no doubt, but the effect even then is to a 
great extent mechanical. The soil is so saturated that drainage 
is impeded, the plants cannot assimilate the nutriment fast enough, 
and consequently it decomposes, forming an abundance of acids 
that speedily exert an injurious effect upon the roots, and are 
doubtlessly absorbed into the tissues of the plants in such 
quantities as to produce disease and ultimately death.— Nemo. 
BORDER FLOWERS—LINARIAS. 
A selection of the herbaceous Linarias cannot fail to interest 
the cultivator and admirer of choice border flowers, but some of the 
Linarias can only be seen to the best advantage in their native 
homes. One of the most beautiful is our common Toadflax, Linaria 
vulgaris, which when seen in the limestone districts on railway 
embankments, stone quarries, old walls, and other places is excep¬ 
tionally beautiful. It also thrives under cultivation on the mar¬ 
gins of the shrubbery or on the rockery. In the border it often 
becomes troublesome to the cultivator from its rapid increase. Its 
offspring, Linaria peloria, when once established if not checked 
will soon overrun a large space of ground, especially in light soil. 
I find them useful for cutting where yellow flowers are in demand. 
It is not my intention to enumerate all the species, but to call 
attention to a few. If anyone wishes to have a peculiarity let 
them procure the Three-bird Toadflax, Linaria triornithophora, 
(what a name I) and cultivate it in a compost of sandy peat and 
loam with well-decayed vegetable substance, in a moderately dry 
situation on a rockery exposed to the sun. The Ivy-leaved Toad¬ 
flax, Linaria Cymbalaria, lts white variety and the variegated form, 
are useful for covering old walls and moist places. The purple 
Toadflax, Linaria purpurea, is a distinct and showy plant, but 
seldom seen. The gaping Toadflax, Linaria hians, needs careful 
search, and will well repay any labour bestowed upon it. Linaria 
tristis, L. marginata, L. venosa, and others that might be named, 
seem to be quite forgotten. Any moderately dry situation is suit¬ 
able, and as a rule Linarias prefer sandy soil containing a good 
portion of decaying vegetable matter. They are readily increased 
by seed sown in the open ground in sandy soil in the spring, and 
by division of the plants in the autumn and the spring.— Linaria. 
TRINITY COLLEGE BOTANIC GARDENS, DUBLIN. 
Whether the visitor loves trees, shrubs, plants, and flowers on 
account of their appearance, intrinsic merits, medical properties, 
or beauty, these fine, old, and admirably iaid-out gardens will 
have a special attraction for him. Here the professors from the 
University, College Green, distant about two miles, find materials 
for illustration of their lectures, and occasionally take their pupils 
for practical instruction. Medicinal plants are separately arranged 
and classified. On the occasion of my visit the respected Curator, 
Mr. F. W. Burbidge, was absent in London ; but the foreman, Mr. 
Ivavanagh, took much trouble to point out the many rare and 
beautiful plants in the several glass structures, and the hardy 
collections out of doors, of which the few following notes, from 
memory principally, may have an interest for some of your readers. 
Although situated in the suburbs, owing to the tasteful arrange¬ 
ment of shrubs, &c., there is a complete isolation from city sounds 
and sights ; and as the public are not admitted except on business, 
the horticultural student, amateur or gardener, may pursue his 
studies undisturbed. The borders are planted so as to be objects 
for imitation and general interest to the observer, and such as 
they can have at home, as distinguished from plants arranged 
according to their natural orders. There were fine specimens of 
Dahlias, Asters, Carnations, and of Dianthus Eastern Queen and 
Crimson Belle, the best I have ever seen, and apparently distinct 
from those generally grown. Convenient in an outside border 
was the Cardinal Flower, Lobelia cardinalis, which I was assured 
lives here without the slightest protection, though almost extinct 
in outdoor country gardens owing to the severity of the last few 
winters’ frost. The same is true of the shrubby Yeronicas and 
many others now flowering, such as Schizostylis coccinea. In 
fact many plants seem to reach dimensions not usually attained 
elsewhere, probably owing to the salubrious situation and the 
protection of high walls, except on the south. 
The south-east winding border is well arranged for effect, with 
a background of such tall plants as Hollyhocks, Sunflowers (many 
of them were double) a stand of similar blooms at the last Dublin 
Flower Show were much admired, tall Phloxes, with the dwarfer 
varieties near the margin, brightened here and there by the Flame 
Flower (Tritoma Uvaria), and with such dwarf plants as Acaena 
microphylla near the edge. The glass structures contain many 
rare and good plants. Very few Orchids, though the collection 
is considerable, are now blooming, though all seemed healthy, per¬ 
fectly free from insects, and well grown. A handsome specimen 
of Oncidium flexuosum deserves notice, owing to the number of 
blooms it contained. The Lattice Plant (Ouvirandra fenestralis) 
seems here to do remarkably well grown under water which is 
very pure. It is planted in an ordinary 2^-inch pot in peat, 
and this is plunged in a vessel of water. There are many 
aquatic plants and mosses that look very interesting, as Azolla 
pinnata and Salvinia natans grown in pans of water, and with 
which some soil has been commingled. The latter fruits under 
the surface of the water, and the berries produce new plants the 
following year, thus providing for its perpetuation. Filmy Ferns 
seem unusually healthy, the system of growth pursued being to 
lay small pieces of spar on the young rhizomes in the pans to keep 
them growing down in a mass. The fronds were very fine. It 
may interest many readers to refer to the system here pursued of 
Croton and Dracaena propagation—viz., by slitting the stems, 
sawing the side out of a suitable pot, introducing the incised 
portion, and tying tightly around with sphagnum, &c. Rooting 
in a warm temperature rapidly occurs. I noticed the same system 
pursued with slight variation at Roebrick Castle and Powerscourt. 
I cannot conclude without referring to the fine fruit produced on 
a specimen Musa Cavendishii, and the small pots in which Mr. 
Burbidge succeeds in growing his Pitcher-plants. For instance, 
a specimen of Sarracenia purpurea was 18 inches high in a 
2^-inch pot, proving that moisture was the principal requisite.— 
W. J. M., Clonmel. 
The Growth of Wellingtonia. —I measured one of these 
trees a few days since which was planted on the day of the 
marriage of the Prince of Wales, March 10th, 1863. Its circum¬ 
ference 6 inches above the ground is 9 feet 7 inches. This seems 
to me to be very remarkable. An Oak would be growing 150 
years before it attained such dimensions. It has often occurred to 
me that owners of large estates would do well to cultivate this 
