270 



FARMERS' REGISTER. 



[No. 5 



thouc:h the plant properly belongs s to the cyanic, 

 yet it is so lar confbrnrmble to naiure, as to help 

 us, to predict the chanijes in color wliich the flow- 

 ers of any plant may undergo. 



White is nor mentioned in cither series, be- 

 cause it is doubted whether it exists in a state of 

 purity in any (lower ; it seems, rather to be some 

 other color, reduced to an exceedingly light tint. 

 Jledouie, a celebrated French flower painter, is 

 said to liave availed himself, with great advan- 

 tage, ol" this. fact. He alwa3's placed the flower 

 he wished to paint, upon a sheet of paper, like 

 that on which he made his drawing; and he in- 

 variably Ibund, that the flower would differ from 

 the paper, in being more yellow, or more blue, or 

 in some other way. Infusions of white flowers 

 in alcohol, have always a perceptible tinge. 

 Many flowers apparently white, yield an infusion, 

 which the action ol" an alkali brings to a decided 

 yellow; many others yield infusions, which the 

 action of an acid brings to a decided red, thus in- 

 dicating, in the first case, the presence of the 

 xanthic chromule ; in the second, the presence of 

 the cyanic chromule. Black is omitted in the 

 two series of colors, because it appears, in all 

 cases, to be an excessively dark shade of purple 

 or brown. When the circumstances are unlavo- 

 rable to the color, black flowers (as they are call- 

 ed) always appear of some lighter shade. The 

 flowers of the false-choke-dog {gonolobus obli- 

 qaus) which are as nearly black as any growing 

 in this country, appear light-purple, when they 

 are produced during a long rainy season. 



Respecting the manner in which the odorife- 

 rous principles of plants are produced, still less is 

 known tlian about their colors. We are gratified 

 by the sweet odors exhaled from the leaves and 

 flowers which surround us, and exert our skill so 

 to preserve ihem,that we may have them always 

 at coiTimand; but as to the reason why one plant 

 is odoriferous and another is not, or why one plant 

 gives rise to one Kind of odor, and another to ano- 

 ther, we have to confess ourselves entirely igno- 

 rant. Still there are some facts respecting odors, 

 which have been learned by observation, which 

 it may be worth the while to mention. All odors 

 are owing to the disengagement of volatile mat- 

 ter; and as there are iew organized bodies in 

 which, in their natural state, there is not some vo- 

 latile constituent part, so neither are there many 

 absolutely destitute of smell. But it is only those 

 plants, and parts of plants, whose scent is very 

 perceptible to our senses, that we term odoriferous, 

 and to these we Will confine our attention. 



Odors are divided by botanists into two clashes, 

 viz: permanent and fugitive. When the vola- 

 tile matter is concentrated, and so enclosed in the 

 the cells, as (0 disperse closely, it gives rise to a rr-r- 

 manent odor. Of this many instances are ;. 'lard- 

 ed by the wood and bark of trees. The wood and 

 bark, being the only permanent parts of vegeta- 

 bles, will of necessity, be the only receptacles of 

 permanent odors. Such parts are not scented, be- 

 cause of their own proper nature, for all the tis- 

 sues of plants are, in themselves, desliiuie of 

 odor, or nearly so. The odors arise entirely, fi-om 

 the fi-agrant secretions imprisoned in their cavi- 

 ties; and their permanence depends upon the dif- 

 ficidty, which these secretions experience, in es- 

 cajiinir through the tissue which encloses thern, 

 ami idso upon the degree in which the secretions 



axe in themselves volatile. Resinous woods, such 

 as the cedar and pine, retain their fragrance for an 

 indefinite period; because the resinous matter in 

 which their odors reside is not in itself very vola- 

 tile, and is moreover imprisoned in thick stout 

 cells. The rose-wood of Tenerifle preserves its 

 odor for a great length of time; and in order to 

 elicit ii, it is necessary to rub the wood strongly, 

 so as to brealv the cells, and also, to produce heat 

 enough to volatilize the matter enclosed in them. 

 The necessity of a certain degree of heat, to pro- 

 duce an exhalation of the volatile matter of some 

 plants, is farther exemplified in the fragrance of 

 many kinds of wood, otherwise scentless, when 

 exposed to the violent friction of a turner's lathe. 

 Beech, in such circumstances, gives out an odor 

 similar to that of roses. Where the odoriferouf? 

 matter is rather volatile, and enclosed in cells of 

 a loose texture, woods soon lose their peculiar 

 odors, as is the case with the bark of the cinna- 

 mon. 



Fugitive odors, are such as belong to perisha- 

 ble organs, or are placed in tissues of the very- 

 loosest texture, or are situated on the surface of 

 plants, or are secreted in quantities so small, that a 

 short exposure to the atmosphere is sufficient to 

 dissipate them. Such odors are produced only 

 during the life of the plant, are dissipated almost 

 as soon as formed, and, after the death of the 

 plant, leave no trace of their existence behind. 

 Like permanent odors, they are continually given 

 oflT; and in some plants, as the violet, without 

 any variation in intensity, in diflierent states of the 

 atmosphere. But in most cases, the intensity of 

 the odor will vary, according to the elevation of 

 the temperature, and the dampness of the air. 

 This fact must be fiimiliar to all acquainted with 

 flowers. In a hot summer's noon, flowers become 

 scentless, or at least, lose a large portion of their 

 usual fragrance ; so that in walking amongst 

 the most sweet-smelling plants, we discover no 

 signs of their odor, unless we bruise or trample 

 upon them. But let a heavy shower come on, 

 and all will be changed in an hour's time ; every 

 leaf, every flower, will emit its peculiar odor. 

 The same thing may be noticed during the dry 

 days towards the close of summer. "Those only 

 who are accustomed to take their walks early, can 

 have any idea of the difference between a richly 

 stored garden, or flowery-meadow, early in the 

 morning, and at noon. VVhen the sun has dried 

 the air, and been beating for some time upon ve- 

 getation, however beautiful the garden or the 

 meadow may still remain, it cannot be compared 

 with the same place before the dew had dispersed; 

 when every herb, tree, and flower is pouring forth 

 a St reaiB of of the most varied and delicious fra- 

 grance, when the air is loaded with the most deli- 

 cate odors — and when all nature seems as if offer- 

 ing up incense in gratitude for the descent of the 

 refreshing dew." To what cause this difference 

 is owing is not well ascertained. Possibly the 

 effect of dryness, and excessive heat, may be to 

 close the stomas or breathing pores, and to con- 

 tract the tissues of the plant, thus rendering it dif- 

 ficult for volatile matter to pass through the cu- 

 ticle ; it may also act, by depriving them of the 

 portion of water necessary to enable I hem to perform 

 their functions, and thus arrest for a time, the pro- 

 duction of the odorifiirous principle on which their 

 fragrance depends. While, however, dew and 



