478 MICROSCOPICAL OBSERVATIONS 



Brongniart himself, of a very elaborate and valuable me- 

 moir, entitled " Becker dies sur la Generation et le Deve- 

 loppement de VEmhryon dans les Vegetaux Flianerogames'' 

 which he had then read before the Academy of Sciences of 

 Paris, and has since published in the Annates des Sciences 

 Naturelles. 



Neither in the abstract referred to, nor in the body of 

 the memoir which M. Brongniart has with great candour 

 given in its original state, are there any observations, ap- 

 pearing of importance even to the author himself, on the 

 motion or form of the particles ; and the attempt to trace 

 these particles to the ovulum with so imperfect a knowledge 

 of their distinguishing characters could hardly be expected 

 to prove satisfactory. Late in the autumn of 1827, how- 

 ever, M. Brongniart having at his command a microscope 

 constructed by Amici, the celebrated professor of Modena, 

 he was enabled to ascertain many important facts on both 

 these points, the result of which he has given in the 

 notes annexed to his memoir. On the general accuracy 

 of his observations on the motions, form, and size of the 

 granules, as he terms the particles, I place great reliance. 

 But in attempting to trace these particles through their 

 Avhole course, he has overlooked two points of the greatest 

 importance in the investigation. 



16] For, in the first place, he was evidently unacquainted 

 with the fact that Jhe active spherical molecules generally 

 exist in the grain of pollen along with its proper particles ; 

 nor does it appear from any part of his memoir that he 

 was aware of the existence of molecules having spontaneous 

 or inherent motion and distinct from the peculiar particles 

 of the pollen, though he has doubtless seen them, and in 

 some cases, as it seems to me, described them as those 

 particles. 



Secondly, he has been satisfied with the external appear- 

 ance of the parts in coming to his conclusion, that no par- 

 ticles capable of motion exist in the style or stigma before 

 impregnation. 



That both simple molecules and larger particles of diffe- 

 rent form, and equally capable of motion, do exist in these 



