THE PISTIL. 



79 



the plant directly exposed to the air, which is destitute | 

 of the epidermis. The importance of the Ovary is such, 

 that it will be treated of in a chapter by itself. At fig. 

 15 is the pistil of the Meadow Safiron. The ovary is 

 nearly mature. It bears a short, pointed, permanent 

 style on each of its three divisions, and the ovules on its 

 inner walls. At fig. 21 is a transverse section of the 

 ovary in the same plant, before its parts separate, show- 

 ing how the ovules are at first deposited. 



444. The Pistillate system collectively is called the 

 Gynoscium. 



445. The degrees of coherence or separation in the 

 styles may be indicated by describing them as distinct, 

 united at the summit, United to the m,iddle, or at the 

 hase, as the case may be. 



FUNCTIONS OF THE STAMENS AND PISTILS. 



446. The joint action of the stamens and pistils must 

 now bo explained, for this is one of the most important 

 processes in nature. Its specific object is the fertilizing 

 of the ovules, and the PRODncTioN of seed. 



447. When the stamens and pistils have reached 

 maturity, the anthers, being acted on by moisture and 

 other causes, discharge their pollen. Under ordinary 

 circumstances, a part of this, almost as a matter of 

 course, falls on the stigma, which at the same time is 

 covered with a viscid moisture. The pollen grains being 

 soon afiected by the moisture, expand. The extine 

 bursts, while the intine is protruded in the form of a 

 tube. The tube insinuates itself between the cells of the 

 stigma, passes down into the style, and finally reaches 

 the ovary. Thence it is extended toward the ovules, 

 and enters the orifice that leads into their nucleds, 

 which, at this time, is always turned toward the base of 

 the style, and in direct communication with its conduct- 

 ing tissue. At fig. 7, two of these pollen tubes from the 

 Snapdragon, are represented as passing through the tube 

 of the stigma. At fig. 8 is a separate tube from the 

 Purple Orchis, and a pollen mass of the same. All that 

 is certainly known of this very curious process is, that 

 the embryo first appears in the ovule soon after the en- 

 trance of the pollen tube. 



448. The Author of Life has made many pro- 

 visions to promote and secure this result. In the first 

 place, the stamens and pistils are generally associated, by 

 being brought together in the same flower. This may 

 be_assumed as the true or normal position, and all others 



Name of the Pistillnte system. How may coherence of the styles be de- 

 scribed? Specific use of Stamens and Pistils. Describe the process of fertiliza- 

 tion. What the only fact known of it ? Normal position of Stamens and Pis- 

 tils — when the flower is erect, how are they— how when it is drooping — what 



as the effect of suppression. When the flower is erect, 

 the pistil is the longest, as in the Tulip ; but when the 

 flower is drooping, as in the Lily, fig. 17, the stamens are 

 longest ; so that, in both cases, the pollen would neces- 

 sarily fall in the direction of the stigma. In the Bar- 

 berry and Mountain Laurel, the filaments are very elastic, 

 and when touched by any small body, as the feet of in- 

 sects, they spring forward with great force, and dash 

 their pollen against the stigma. 



449. Monoecious and Dioecious flowering trees gene- 

 rally put forth their blossoms at windy seasons of the 

 year, when there are no leaves to obstruct the course of 

 the pollen, which in those tribes is very abundant. It 

 spreads over the trees in all directions, and thus passes 

 to the flowers without interruption. This work is also 

 gi-eatly assisted by insects, which, in abstracting honey 

 from the flowers, scatter their pollen, and carry it from 

 flower to flower ; thus conveying to the fruitful but soli- 

 tary tree or herb, the means of fertilization. 



450. There are also many curious contrivances to pro- 

 mote this object. In the Saxifrage and Pamassia, the 

 stamens, one or two at a time, lean over the stigma, shed 

 their pollen, and retire, to make room for others. The 

 five fllaments of the Coxcomb are connected at base by a 

 membranous web, which expands with moisture ; but 

 contracting in dry weather, it brings the stamens together, 

 and scatters the pollen on the stigma. 



451. But there is nothing of this kind more curious 

 than the habit of the Vallisneria, which is found growing 

 at the bottom of ditches in Italy, and is represented at fig. 

 20. The fertile flowers grow on long, spiral stalks, 

 which, when the stigma is mature, uncoil themselves, 

 and thus elevate the flowers above the surface. At the 

 same time, the barren flowers, which grow on short, 

 straight stalks at the bottom, become detached, rise to 

 the surface, and float around among the pistillate flowers, 

 often covering the water, as if with sprinklings of white 

 foam. Soon after this happens, the pistillate flower- 

 stalks resume their spiral form, and sink to the bottom, 

 where they ripen their seed. 



452. In the Fig, where the flowers are not only dioe- 

 cious, but are borne on the inside of the hollow receptacle 

 which becomes the fruit, the fertilization could only be 

 accomplished by means of insects passing from the bar- 

 ren to the fertile flowers. 



453. But the habit of the Aristolochia is even more 

 peculiar, for it has a particular insect which seems devoted 



effect ? How are the fllaments in the Monntain-Lanrcl — the Barberry ? How are 

 Monceeious and Dicecions trees fertilized ? Of what use are insects ? What 

 curious contrivances ? How in the Saxifrage and Pamassia — ^the Coxcomb ? 

 Describe fertilization of Vallisneria — Aristolochia. How is the Fig fertilized? 



