OSGANS OF RErEODUCTION. 



C3 



tree, which blossomed every summer, but with- 

 out producing any fruit capable of germinating; 

 as this gentleman had frequently sown the seeds 

 it yielded, in the hope of raising more plants, 

 but without success. At last, however, he was 

 advised by Jussieu and Du Hamel to endeavour 

 to procure a male plant and place this near it. 

 Accordingly a male plant was procured, in the 

 following year, full of flowers, and placed near 

 the female, the result being, as in other cases of 

 a similar kind, that the seed now produced was 

 capable of germinating when sown. But when 

 the male plant was afterwards removed, the 

 fruit of the female plant was found to be again 

 incapable of germinating. In the month of 

 April, 1752, Linnaeus sowed a few grains of 

 hemp seed in two different pots, in both of 

 which it came up very well. In the one pot he 

 left the male and female plants together, which 

 flowered and produced fruit that was ripe in 

 July ; from the other pot he removed all the 

 male plants as soon as they could be distinguished 

 from the females, which grew indeed very well, 

 and presented their long pistils in great abund- 

 ance, as if in expectation of their mates. But 

 when the calyxes were afterwards inspected 

 about the time that the pistils began to decay 

 through age, though they were large indeed, 

 and luxuriant, yet the seed buds were brown, 

 compressed, and membranaceous, without exhib- 

 iting any appearance of cotyledons or pulp. 

 Two plants of clutia tenella were in like manner 

 kept growing in a window in Linnaeus's house, 

 during the summer months, the male and female 

 plants being in separate pots. The female 

 plants abounded with flowers, not one of which 

 proved abortive; the pot containing the male 

 plants was after some time removed to a different 

 window in the same apartment, and stiU the 

 flowers that were protmded under such circum- 

 stances were found to be fniitful. The pot con- 

 taining the male plant was at last removed into 

 a different apartment, and the female plants left 

 alone, after being stripped of all the flowers al- 

 ready expanded. They continued to produce 

 new flowerg every day, from the axUs of every 

 leaf, but they proved to be all abortive. For 

 after remaining on the plant for the space of 

 eight or ten days, till the foot stalks began to 

 turn yellow, they all fell barren to the gi'ound. 

 Such is the amount of the great body of facts, 

 resulting both from observation and experiment, 

 on which Linnseus has established the doctrine 

 of the sexes of vegetables, and on which the im- 

 portant and irresistible conclusion depends, that 

 no seed is perfected without the previous agency 

 of the pollen. 



To complete this subject we must, however, 

 allude to the objections which were raised to 

 the theory of the sexuality of vegetables about 

 tlie time when this theory was not yet com- \ 



pletely established by the foregouig accmuuk- 

 tion of facts. 



Camerarius, who had infen-cd the tnith of 

 the doctrine from the result of actual experi- 

 ment, which he was indeed the first to institute 

 on the subject, seems after all to have found 

 cause to doubt the legitimacy of his conclusion, 

 in observing that some of the female plants on 

 which his experiments were made, such as hemp, 

 spinach, and mercury, produced also ripe and 

 perfect seeds, even when placed altogether be- 

 yond the reach of the influence of the male 

 plants. This fact looked, no doubt, extremely 

 hostile to the doctrine he was endeavouring to 

 establish, and perhaps constituted to him an 

 insuperable objection; but the fact has now 

 been sufficiently accounted for, and consequently 

 the objection obviated. For it has been ascer- 

 tained, by means of more minute and accurate 

 observations, that the fertile plants of the genera 

 in question have often some latent male flowers 

 interspersed among their female flowers, so 

 that the former, though difficult of detection, 

 are sufficient to secure the impregnation of the 

 latter, even when the individual producing tJiem 

 is solitary. Toumefort, who denied the doctrine 

 of the sexes altogether, though on insufficient 

 grounds, admitted, however, the utility of the sta- 

 mens in the economy of fructification, regarding 

 them as organs both of secretion and excretion, 

 the substance excreted being the pollen, and the 

 substance secreted being a peculiar fluid that 

 was conducted by the filaments to the geimen. 

 But if the pollen is merely an excrement, how 

 comes it to be so very curiously organized ? 

 And if the stamens secrete a fluid which they 

 afterwards conduct to the germen, by what 

 means do they conduct it when placed on a 

 different plant 1 Pontedera, who was one of the 

 most zealous disciples of Toumefort, and willing 

 to defend him, even when least defensible, not 

 only adopted the opinions of his master on this 

 subject, but endeavoured to establish them by 

 additional argument, contending that if the 

 stamens and pistils were even destined to the 

 discharge of the functions ascribed to them by 

 the sexualist, yet there are many cases of perfect 

 fi-uctification in which they could not possibly 

 co-operate to the production of the effect. Ad- 

 ducing the example of the umhelliferce, in which 

 the style, as he rightly remarked, does often not 

 appear till after the stamens have fallen. But 

 although the styles remain often inconspicuous 

 tm the period assigned by Pontedera, yet the 

 stigma is previously mature, and consequently 

 capable of the necessary co-operation. But if 

 the fact had been precisely what it appears to 

 be in the objection, stUl it would have afforded 

 no formidable argument against the doctrine of 

 the sexes. For as the several flowers of the 

 same plant, and much more the flowers of 



