ON ACTIVE MOLECULES. 479 



parts, before the application of the pollen to the stigma can 

 possibly take place, in many of the plants submitted by him 

 to examination, may easily be ascertained ; particularly in 

 Antirrhinum majus, of which he has given a figure in a 

 more advanced state, representing these molecules or parti- 

 cles, which he supposes to have been derived from the 

 grains of pollen, adhering to the stigma. 



There are some other points respecting the grains of 

 pollen and their contained particles in which I also differ 

 from M. Brongniart, namely, in his supposition that the 

 particles are not formed in the grain itself, but in the cavity 

 of the anthera ; in his assertion respecting the presence of 

 pores on the surface of the grain in its early state, through 

 which the particles formed in the anthera pass into its 

 cavity ; and lastly, on the existence of a membrane forming 

 the coat of his boyau or mass of cylindrical form ejected 

 from the grain of pollen. 



I reserve, however, my observations on these and several 

 other topics connected with the subject of the present in- 

 quiry for the more detailed account, which it is my intention 

 to give. 



July 30M, 1828. 



ADDITIONAL REMARKS ON ACTIVE 

 MOLECULES. 



By ROBERT BROWN, F.R.S. 



About twelve months ago I printed an account of Mi- 

 croscopical Observations made in the summer of 1827, on 

 the Particles contained in the Pollen of Plants ; and on the 

 general Existence of active Molecules in Organic and In- 

 organic Bodies. 



