ORUANS OK FRUCTIFICATION. 



0.5 



not luave reached tlie insulated plants by means 

 of a favourable combination of circumstances ; 

 and in the next place, it is not certain tliat the 

 plants in question were not furnished with some 

 minute and latent male flowers, by which the 

 impregnation might have been effected. The 

 next most formidable ojjponent was Spallanzani. 

 His first experiment was made upon the ocyimim 

 basilicum, an hermaphrodite plant, the anthers 

 of several flowers being all cut off before the 

 pollen was ripe, and the stigmas carefully se- 

 cured from the access of the pollen of other 

 flowers, in which case it was found that most of 

 the seeds produced were evidently imperfect; 

 though there were also a few that seemed to be 

 completely matured by their exhibiting, on dis- 

 section, tlie same appearances as others that had 

 been exposed to the action of the pollen. But 

 when those apparently perfect seeds were put to 

 the proper test, they were found to be in reality 

 imperfect; they did not germinate when sown. 

 Tills result was sufficiently discouraging, but it did 

 not deter him from anotlier attempt. The sub- 

 ject of his next experiment was from the class 

 monmcia, the citcurUta citi'ullus, the male flowers 

 of which were destroyed as soon as they made 

 tlieir appearance, and the female flowers, in order 

 to prevent all suspicion of the access of pollen, 

 were inclosed in bottles, luted to the stem by 

 the neck so as to exclude even the external air. 

 Tlie seeds which were procured in this way, 

 genninated and produced plants. This result 

 was as favourable to SpaUanzani's opinion as 

 could be wished, liut to give to the argument 

 against the sexes all the weight lie could, ho 

 now directed his attention to the class dicscia, 

 selecting as the subject of experiment some 

 plants of particular families, from which he ob- 

 tained results equally favourable to his views. 

 For after taking every precaution to secure tlie 

 female plants from the access of pollen, as in the 

 above example, seeds were still procured that 

 germinated when sown. From all which ex- 

 periments he was inclined to think that the 

 pollen is not in any case essential to fecundation. 

 If to these, however, we oppose the experiments 

 of Linnseus, and others already detailed, the 

 preponderance of facts is greatly in favour of 

 the sexual theory. Even although the experi- 

 ments instituted by Spallanzani were rather 

 favourable to his views, yet he does not seem, 

 after aU, to put implicit confidence in them, 

 thinking that the opposite doctrine may stiU be 

 true, that the ripening of the seeds that were 

 perfected without the poUen, might have been 

 effected by means of a power, inherent in the 

 female flowers, of propagating to a certain number 

 of germinations without the assistance of the 

 m.ile, in the same way as Bonnet had shown 

 that the aphis insect does, and as he had himself 

 obsen-ed take place in some other plants which 



propagated in this way for three generations. 

 Spallanzani suggests also the possibility of the 

 fecundation of tho ovary by means of some 

 seminal principle residing in the pistil, and 

 capable of supplying the place of the pollen as 

 well as necessary in the case of monoecious and 

 dioecious plants, to ensure the perfection of the 

 seed. This conjecture is perhaps countenanced 

 in some degree by Koelreutcr's account of the 

 chemical properties of the moisture exuding 

 from the stigma when ripe, which ho represents 

 as being precisely the same with the chemical 

 properties of the pollen. But this is leaving tho 

 matter precisely as it was taken up; for if the 

 suggestion of Spallanzani is true, then there 

 exists at least a virtual sexuality in vegetables. 



CHAP. XIII. 



GROANS OF FBUCTIFICATIOX. 



Flowers exist in the incipient state in the 

 bud long before the period of their evolution. 

 If the scales of a leaf bud are taken and stripped off 

 and the remaining part carefully opened up, it will 

 be found to consist of the rudiments of a young 

 branch terminated by a bunch of incipient leaves 

 imbedded in a white and cottony down, being 

 minute, but complete in all their parts and pro- 

 portions, and folded or rolled up in the bud in 

 a peculiar and determinate manner. This has 

 been called the foliation of plants. If the scales 

 of a flower bud are taken and stripped off, and 

 the remaining part carefully opened up, it will 

 be found also to consist of the rudiments of an 

 incipient flower, exceedingly small and minute, 

 but complete in all its parts. This operation 

 was performed in the month of January, by 

 Du llamel, on the bud of a pear tree, and the 

 following was the result. The scales, which 

 were from twenty-five to thirty in number, 

 were found to contain from eight to ten flowers, 

 attached to a common foot stalk of half a line 

 in length. The flowers in their general aspect 

 resembled rose buds set with haire. The petal.s 

 were scarcely perceptible, but the filaments were 

 distinctly visible, surmounted with white an- 

 thers. The pistils were not yet visible, but they 

 became so in the following month, when the 

 anthers had begun to assume also a tinge of red. 

 The ovary was not distinguishable in the earlier 

 dissection, but it became so before the evolution 

 of the bud. Similar appearances may bo seen 

 by opening up the flower buds of almost any 

 plant, long before the time of their natural 

 evolution. The mezereon produces its flowers 

 in the month of January or February ; but if a 

 bud be taken and dissected in the month of 

 Augnst preceding, the petals, the stamens, and 



