Origin and Development of the Vegetable Embryo. 51 



to presume, from his knowledge of the researches of MM. Brown 

 and Ad. Brongniart, that there was no essential difference in the 

 mode of fertilization in these families, M. Amici goes on to say 

 that he considered new researches necessary to the confirmation 

 of his conjectures, and this more than ever after the publication 

 of the supplemental note of Mr. Brown, in which the " mucous 

 tubes," instead of being regarded as pollen-tubes, were stated to 

 be apparently distinct from them, although engendered or pro- 

 duced by their influence. If this last statement were incontest- 

 able, not only would Schleiden's theory be totally overturned, 

 but Amici's idea, that the elongation and penetration of the 

 pollen-tube into the coats of the ovule is a general law, would be 

 devoid of ground. 



The want of means and leisure had prevented the prosecution 

 of his researches on this subject until the publication of Gaspa- 

 rini's observations on Cytinus hypocijstis revived M. Amici's desire 

 to determine these points, and he commenced a minute investi- 

 gation of the organs of fructification of the Orchidacece. These 

 have confirmed him in the earlier opinion of Mr. Brown, and he 

 regards the strings of tubes descending into the ovary as really 

 bundles of pollen-tubes. He has moreover been able to deter- 

 mine the precise state of the ovule before the arrival of the pollen- 

 tube ; then, how the latter penetrates the coats and behaves in 

 relation to the embryonal vesicle ; and lastly, observed the imme- 

 diate changes which follow, in the ovule, the introduction of the 

 pollen-tube. All these go to support his former observations, 

 and exclude the idea of the conversion of the extremity of the 

 pollen-tube into the embryo. 



In the first place is offered the evidence on which he founds 

 the opinion that the six bundles or cords of tubes descending into 

 the ovary are prolonged pollen-tubes. Regarding the description 

 of the appearance and course of these tubes, given by Mr. 

 Brown, as altogether agreeing with the characters of pollen- tubes 

 in other phanerogamous plants, it only remained to determine 

 the identity of the pollen-tubes attached to their granules, and 

 entangled in the thickness of the stigma, with the other tubes 

 of a supposed different origin, and (hypothetically) produced in 

 the immediate vicinity of the former ; this identity was established 

 several times by compressing the stigma between two glass plates, 

 and observing that the tubes were continuous with each other. 

 The slight peculiar characters proposed to be founded on the 

 coagulations, &c. in the "mucous tubes," Amici considers valueless 

 for distinguishing them from pollen-tubes ; these coagulations, 

 sometimes interruptions of the continuity of their cavities, being 

 consequent on the gradual withering of the layers of the stigma 

 and style, which interferes with the communication with the parts 



4* 



