THE 



PHILOSOPHICAL MAGAZINE 



AND 



ANNALS OF PHILOSOPHY. 



[NEW SERIES.] 



SEP T EMBER 1828. 



XXVII. A brief Account of Microscopical Observations made 

 in the Months of June, July, and August, 1827, on the Par- 

 ticles contained in the Pollen of Plants ; and on the general 

 Existence of active Molecules in Organic and Inorganic Bodies. 

 By Robert Brown, F.R.S., Hon. M.R.S.E. $ R.I. Acad., 

 V.P.L.S., Corresponding Member of the Royal Institutes of 

 Prance and of the Netherlands, Sfc. fyc. 



[We have been favoured by the Author with permission to insert the fol- 

 lowing paper, which has just been printed for private distribution. — Ed.] 



r | 1 HE observations, of which it is my object to give a sum- 

 A mary in the following pages, have all been made with a 

 simple microscope, and indeed with one and the same lens, 

 the focal length of which is about ^nd of an inch*. 



The examination of the unimpregnated vegetable Ovulum, 

 an account of which was published early in 1826f, led me to 

 attend more minutely than I had before done to the structure 

 of the Pollen, and to inquire into its mode of action on the 

 Pistillum in Phaenogamous plants. 



In the Essay referred-to, it was shown that the apex of the 



* This double convex Lens, which has been several years in my pos- 

 session, I obtained from Mr. Bancks, optician, in the Strand. After I 

 had made considerable progress in the inquiry, I explained the nature of 

 my subject to Mr. Dollond, who obligingly made for me a simple pocket 

 microscope, having very delicate adjustment, and furnished with ex- 

 cellent lenses, two of which are of much higher power than that above 

 mentioned. To these I have often had recourse, and with great advantage, 

 in investigating several minute points. But to give greater consistency to 

 my statements, and to bring the subject as much as possible within the reach 

 of general observation, I continued to employ throughout the whole of the 

 inquiry the same lens with which it was commenced. 



T In the Botanical Appendix to Captain King's Voyages to Australia, 

 vol. ii. p. 5.34. et seq. 



New Series. Vol. 4-. No. 2 1 . Sept. 1828. Y nucleus 



