ORGANS OF REPRODUCTION. 



CI 



generally the longest, as in the ranunculus. In 

 simple and hermaphrodite flowers, the situation 

 of the pistil is invariably central with regard to 

 that of the stamens, as may be seen by examin- 

 ing any kind of flower. In plants of the class 

 Monoecia the barren blossoms stand generally 

 above the fertile blossoms, even when situated 

 on the same footstalk, as may be seen in the 

 case of the carex and arum. And in plants that 

 have their barren and fertile flowers on distinct 

 individuals, the blossom is generally protruded 

 before the leaves expand. But a very little re- 

 flection will serve to show that all the above ar- 

 rangements are institutions of nature, by which 

 the pollen, when it explodes from its envelopes, 

 shall possess the best possible chance of coming 

 into contact with the pistil or stigma. And 

 when such means are wanting, nature displays 

 a variety of other contrivances to effect the same 

 end. The style of the gloriosa superba is bent 

 towards the stamens at a right angle, even from 

 the very base, and for no other conceivable pur- 

 pose but that of throwing itself in the way of 

 the pollen when discharged. The stamens of 

 the saxifrages bend down to the pistil one or 

 two at a time; if two, those then are opposite 

 each other, and discharge their pollen directly 

 over the stigma, returning afterwards to their 

 fonner position, and giving place to one or two 

 others successively, which also retire in their 

 turns tiU all of them liave discharged their poUen. 

 Similar effects have been observed in the flowers 

 of the garden rue and others. But the most 

 singular example of this kind is that which is 

 exhibited in the stamens of the flower of the 

 berberry bush; the stamens, which are six in 

 number, lie sheltered under the concave lips of 

 the petals, as long as they are allowed to remain 

 undisturbed; but if any extraneous body, whether 

 by accident or design, is made to touch a stamen 

 at the base of the filament, it immediately col- 

 lapses with a sudden jerk, and bends inward till 

 the anther strikes against the summit of the 

 pistil, discharging its pollen if ripe, and again 

 retiring. This curious and singular fact seems 

 to have been first discovered by Sir J. E. Smith. 

 The experiment may easily bo tried by applying 

 the point of any instrument, sufliciently delicate, 

 to the inner side of the base of the stamen, when 

 it will immediately spring forward till it strikes 

 against the pistil ; and it is to be presumed, that 

 the same effect is produced in the natural order 

 of things, by means of the feet or trunks of 

 insects rummaging the flower in quest of honey. 

 The economy of many of the aquatic plants, 

 seems also expressly intended to facilitate the 

 process of impregnation. Many plants of this 

 class that vegetate, for the most part, wholly im- 

 mersed in water, and often at a considerable 

 depth, gradually begin to elevate their stems, as 

 the season of flowering advances, when they at 



last rear their heads above the surface of the 

 wat-er, and present their opening blossoms to the 

 sun till the petals have begun to fade, when 

 they again gradually sink down to the bottom 

 to ripen and to scatter tlieir seeds. This very 

 peculiiu- economy is seen in the case o{ puppia 

 maritima, and several species of rotamogeton, 

 which are common in our ponds and ditches ; 

 from which we may fairly infer, that the flowera 

 rise thus to the surface merely to give the pollen 

 an opportunity of reaching the stigma uninjured. 

 But the most remarkable example of this kind 

 is that of the valisnaria spiralis, a plant tluit 



87. 



grows in the ditches of Italy. The plant belong 

 to the, class Dicecia producing its fertile flowers 

 on the extremity of a long and slender stalk, 

 tvristed spirally like a cork screw, which uncoil- 

 ing of its own accord about the time of the 

 opening of the blossom, elevates the flowers to 

 the surface of the water, and leaves them to ex- 

 pand in the open air. The barren flowers are 

 produced in great numbers upon short upright 

 stalks issuing from a different root, from which 

 they detach themselves about the time of the 

 expansion of the female blossoms, mounting up 

 like little air bubbles, and suddenly expanding 

 when they reach the surface, where they float 

 about in great numbers among the female blos- 

 soms, and often cling to them in clusters so as 

 to cover them entirely ; thus bringing the stamens 

 and pistils into immediate contact, and giving 

 the anthers an opportunity of discharging their 

 pollen immediately over the stigma. When 

 this operation has been performed, the now un- 

 coiled stalk of the female plant begins again to 

 resume its original spiral form, and gradually 

 sinks down as it gradually rose, to ripen its froit 

 at the bottom of the water. 



Such are the proofs of the sexuality of vege- 

 tables, arising from the observation of the na- 

 turtd phenomena exhibited in the economy of 

 flowers ; we shall now enumerate those proofs 

 deduced from experiment. If the anthers of an 



