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Such of the readers of ' The Phylologist' as have not seen an arti- 

 cle in the 'Microscopic Journal' (ii. 138), by Herbert Giraud, M.D., 

 ' On the origin and development of the embryo in Tropaeolum majus,' 

 will do well to consult it. W. Wilson. 



Wan-ington, July 7, 1843. 



[We give below Dr. Givaud's article from the ' Proceedings of the Linnean Socie- 

 ty,' where it originally appeared. — Ed.'] 



" After referring to the researches of MM. Schleiden, Wydlev, Mirbel and Spach, 

 and A. St. Hilaire, on this important point, Dr. Giraud states that he was induced to 

 select Tropseolum as the subject of his own observations, on account of its solitary 

 ovula, and their comparatively large size, which render the individuals of this family, 

 as well as the allied Geraniaceas, peculiarly fitted for the purpose. He arranges his 

 observations under seven general heads, coiTesponding with as many progressive pe- 

 riods in the growth of the female organs, and extending from the completion of the 

 anatropous development of the ovule to the perfect formation of the embryo ; or from 

 the commencement of the expansion of the bud to the complete formation of the 

 fruit. The results are collected from a great number of dissections. 



" In the Jirst period, or just before the expansion of the bud, a longitudinal sec- 

 tion of the carpellum from its dorsum towards the axis of the pistillum, dividing the 

 ovule, shows the latter to have completed its anatropous development. A portion of 

 rather firm and dense cellular tissue, enclosing a bundle of vessels, descends from the 

 placenta and in apposition with it to form the raphe, and terminates in the base of the 

 ovule. The nucleus has only one integument, at the apex of which is the exostome 

 or micropyle, opening close by and to the outside of the point of attachment ; and 

 the conducting tissue of the style may be traced into the carpellary cavity as far as 

 the exostome. 



" In the second period, during which the expansion of the bud and the dehiscence 

 of the anthers commence, and therefore, before impregnation, a small elliptical cavity 

 makes its appearance near the apex of the nucleus, having a delicate lining membrane 

 formed by the walls of the surrounding cells : this cavity is the embryo-sac, and a mi- 

 nute canal may be traced leading from it to the exostome. The apex of the embryo- 

 sac encloses at this period a quantity of organizable mucilage, containing many mi- 

 nute bodies, having the appearance and character of cytoblasts. 



" In the third period, the apex of the nucleus and of its integument, becomes 

 slightly inclined towards the placenta. The embryo-sac is much enlarged and length- 

 ened ; its mucilage has disappeared and given place to an elongated diaphanous 

 utricle {utricule primordiale, Mirbel ; vesicule embrijonnaire, Meyen ; extrhnite mite- 

 rieure du boyau pollinirjue, Schleiden) containing a quantity of globular matter or 

 cytoblasts. This primary utricle is developed wholly within the embryo-sac, from 

 which it is obviously distinct. 



" The fourth period occurs after impregnation. The pollen tubes do not extend 

 into the carpellary cavity ; but the fovilla, with its granules, is found abundantly in 

 the passage leading from the style to the exostome. With the increased development 

 of the embryo-sac, the primary utricle elongates and becomes distinctly cellular, by 

 the development of minute cells in its interior, while at the extremity next the base 



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