-K) FLORICULTURE OF TIIE TOILET. 251 
while others have no such peculiarity, e.g. the Fungi, the Orchids, Bog-plants, &c. Lastly, it is 
commonly seen that many plants remain comparatively poor and starvcd-looking when grown in soil 
devoid of organic matter, while others will flourish in soils containing few traces of it. Thus, while 
the Heaths, Brooms, Buckwheat, &c. &c. grow in the poorest soils, the corn-plants require an accu- 
mulation of mould or decayed vegetahle matter to enable them to grow in any degree of luxuriance. 
It is clear, therefore, that there exist many varied conditions among vegetables in regard to the 
character of their food ; that in some the power of assimilating inorganic substances prevails, in others 
there is a necessity for the intermixture of a certain proportion of organic matter, and lastly, in a 
comparatively small number, the true parasites, the organised food is required in a fresh and un- 
altered condition, just as it is delivered by the stock to the graft in our cultivated fruit trees, 
The inorganic compounds most largely absorbed by plants are formed of the four principal ele- 
ments — carbon, oxygen, hydrogen, and nitrogen ; and consist of water, carbonic acid, and ammonia. 
The mode in which water is taken up by plants has been spoken of in a former chapter, in discussing 
the absorption of fluids ; bui, with regard to the carbonic acid it is necessary to enter into some 
further details. Carbonic acid is met with universally, diffused in the atmosphere and dissolved in 
water : in the latter condition it is of course absorbed by the roots of plants, but much more than is 
supplied in this way enters into the vegetable structures ; and it has been proved by experiment that 
the green parts of plants, and in particular the leaves, whenever they are exposed to sunlight, are 
capable of absorbing a great deal of carbonic acid either from ah- or water, and that they set free a 
proportionate quantity of oxygen. It was calculated by Chevandier that the trees of a forest remove 
one-ninth of the carbonic acid contained in the column of air standing over them, during the five 
summer months through which their leaves live. 
The oxygen which is given off appears to be a direct secretion from the superficial green parts, 
and is not contained within the plant for any time in a gaseous condition before it is given off; for 
plants which contain no air, such as Conferva?, or leaves which have been exhausted of their air 
beneath the air-pump, in like manner give off oxygen gas. Pieces of torn leaves possess the property 
as strongly as whole leaves ; but leaves which have had their structure destroyed by pressure give off 
no oxygen, neither does the epidermis. 
According to the researches of Dr. Draper, the amount of oxygen given off is different under 
different rays of the spectrum ; it being found that the effect was proportionate to the illuminating 
power, the chemical and heating rays having no effect at all. The same author found also that the 
gas given off by plants in the sunlight docs not consist of oxygen alone, but always contains a certain 
amount of nitrogen ; and he goes so far as to regard this separation of nitrogen as a necessary and 
even primary phenomenon, indicating the action of a nitrogenous ferment, which causes the decom- 
position of the carbonic acid. Some interesting experiments on this subject were published in this 
Magazine some months back. 
The absorption of carbonic acid and the separation of oxygen which take place in the sunlight, 
form but a part of the processes carried on in the decomposition or recomposition of those elements. 
The alternations which take place between the products given off in the night and in the day is 
clearly made out, and leads to more curious speculation respecting the assimilative processes of plants. 
Of these we shall speak in another chapter, under the head of Respiration. 
FLORICULTURE OF THE TOILET. 
7TIHE floriculture of the toilet embraces the choice, culture', and general knowledge of all those plants 
A which are susceptible of ornamenting the human form. This science, if such it may be called, 
forms the most important feature in hair-dressing, and enters largely into the complete requirements 
of a good education. As a branch of floriculture it ranks among the most ancient inventions; and 
if its laws have not been reduced to system, it has not been for want of examples or of application. 
M. Jules Laehaume, in an elegant work, entitled Natural Flowers, or, a Treatise on the art of 
composing Crowns. Garlands, and Bouquets of all kinds, for Balls and Evening Parties, has been one 
of the first to open up this subject. We translate the following from Lit llelyitjiic Hurlirole : — 
One of the favourite amusements of infancy is to plait crowns with the wild flowers of the woods 
and fields. The timid lover expresses his passion by the homage of a bouquet: and the young belle 
naively abandons to her favourite the flowers which decked her brow or withered ou her bosom. Old 
age itself smiles on (lowers. Crowns and other garlands may be traced to the most remote antiquity. 
Among the Greeks and Romans the crown was, so to speak, the ordinary hair-dress of the great 
I--'*'' g^sgg v3 
