70 



HISTORy OF THE VEGETABLE KINGDOM. 



prominent appendages ; the other internal, thin, 

 transparent, and having no adhesion to the first. 

 When submitted to the action of water, the 

 inner membrane swells, the outer bursts at some 

 part of its surface, and through the opening 

 thus formed there issues a tubular prolongation, 

 which forms a kind of bag, first observed by 

 Needham. Sometimes two prolongations issue, 

 at two opposite points. The cavity of the inner 

 membrane is filled with spherical granules, of 

 extreme minuteness, wliich appear to perform 

 the most important part of the act of fecunda- 

 tion. 



The pollen of the families Asclepiadese and 

 orchidese presents very remarkable modifications. 

 In several genera of these two families, all the 

 pollen contained in a cell is united into a body, 

 which has the same form as the cell in which it 

 is contained. To this united pollen is given the 

 name oi pollen-mass. When the pollen is thrown 

 on red-hot charcoal, it bums and flames with 

 rapidity. In many plants, it diffuses an odour, 

 bearing the most striking resemblance to the 

 substance in animals to which it is compared, as 

 is very distinctly observed in the chestnut and 

 barberry. 



The pollen, when it begins to be developed, 

 and long before the expansion of the flower, 

 presents itself under the form of a cellular mass, 

 sometimes covered with an extremely thin mem- 

 brane, which, however, has no attachment to the 

 walls of the cavity. The utricles of which this 

 mass is composed, are at first very intimately 

 imited together. Some scattered granules are 

 perceived in their interior. By degrees the 

 utricles separate, the granules which they con- 

 tain unite, and by their successive development, 

 soon burst the utricles, assume the form which 

 they are to retain, and finally become grains of 

 pollen. It will be seen that tliis mode of de- 

 velopment is perfectly similar to that of the 

 cellular tissue, which we described when treat- 

 ing of the elementary part of vegetables. 



The pistil is the female organ in plants, cut 

 43. It almost invariably occupies the centre of 

 the flower, and is composed of three parts, the 

 ovart/ a, the style b, and the stigma c. 



In most cases, we find only a single pistil in 

 a flower : as in the lily, the hyacinth, and poppy. 

 At other times, there are several pistils in the 

 same flower; as in the rose and ranunculus. 

 The pistil, or pistils, when there are more 

 tlian one, are often attached to a particular pro- 

 longation of the receptacle, to which the name 

 of gynophorum is given, and which does not es- 

 sentially belong to the pistil, but remains at the 

 bottom of the flower when the pistil is detached. 

 When there are several pistils in a flower, it is 

 not unusual to see the gynophoi-um becoming 

 thick and fleshy. This is particularly observable 

 in the raspboiTy, and strawben-y. The part of 



the latter which is pulpy and sweet, and wliieh 

 is eaten, is merely a very large gynophorum ; 

 and the little shining grains which cover it are 

 so many pistils. It is easy to satisfy one's self 

 as to the nature of these different parts, by fol- 

 lowing their gradual development in the flower. 

 The base of the pistil is always represented 

 by the point at which it is attached to the re- 

 ceptacle. The summit, on the other hand, always 

 corresponds to the point where the styles or the 

 stigma are inserted into the ovary. 



The mary, fig. a, always occupies the lower 

 part of the pistil. Its essential character is, 

 that when divided in the longitudinal or trans- 

 verse directions, it presents one or more cavities, 

 named cells, in which are contained the rudi- 

 ments of the seeds, or the ovules. It is in the 

 interior of the ovary that the omdes acquire all 

 their development, and are converted into seeds. 

 This organ may therefore be considered, with res- 

 pect to its functions, as analogous to the ovary and 

 uterus in animals. Its usual form is egg-shaped; 

 but it is more or less compressed and elongated 

 in certain families of plants, as in the Cruciferse, 

 Leguminoste, &c. The ovary is generally free 

 at the bottom of the flower ; in other words, its 

 base corresponds to the point of the receptacle, 

 into which are inseiied the stamina and the 

 floral envelopes, although it does not contract 

 any adhesion with the calyx ; as is observed in 

 the hyacinth, the lily, and tulip. Sometimes, 

 however, the ovary is not met with in the bot- 

 tom of the flower, but seems to be placed entirely 

 beneath the insertion of the other parts ; in other 

 words, it is united in every part of its circum- 

 ference with the tube of the calyx, its summit 

 alone being free in the bottom of the flower. In 

 this case, the ovary has been named adherent or 

 inferior, to distinguish it from that in which it 

 is free or superior. The genera Iris, Narcissus, 

 Myrtus, and Riles, have an inferior ovary. 



When this organ, 

 '"■ therefore, is not met 



with at the bottom of the 

 flower, but when the 

 centre of the latter is oc- 

 cupied by a style and a 

 stigma, it will be neces- 

 sary to examine if there 

 be not at the bottom of 

 the flower a particular 



0, ovary of gooseberry; p ;,, bulging, distinct from 



miiguifiBd ball of poUun. the top of the peduucle. 

 If this enlargement, on being cut across, presents 

 one or more cavities, containing ovules, it is 

 clear that there is an inferior ovary. 



The position of the ovary, considered as to its 

 being inferior or superior, furnishes the most 

 valuable characters tor grouping genera into 

 natural families. Whenever it is inferior, the 

 calyx is ncccssiwily monosepalotis, since its tubo 



