MICEOSCOriCAL OBSERVATIONS. [3 



The observations, of which it is my intention to give a 

 summary 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 s^nd of an 

 inch.^ 



The examination of the nnimpregnated vegetable Ovu- 

 lum, an account of which was published early in 1826,"^ 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 Phaenognmous plants. 



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

 the nucleus of the Ovulum, the point which is universally 

 the seat of the future Embryo, was very generally brought 

 into contact with the terminations of the probable channels 

 of fecundation j these being either the surface of the pla- 

 centa, the extremity of the descending processes of the style, 



' This double convex lens, wliicli has been several years in my possession, I 

 obtained from Mr. Bancks, optician, in the Strand. After I had made con- 

 siderable progress in the inquiry, I explained the nature of my subject to Mr. 

 Dollond, who obligint,'ly made for me a simple pocket microscope, having very 

 delicate adjustment, and furnished with excellent lenses, two of which are of 

 much higher power than that above mentioned. To these I have oilen had 

 recourse, and with great advantage, in investigating several minute points. 

 But to give greater consistency to my statements, and to bring the subjcc-t as 

 much as possible within the reach of general observation, 1 continued to 

 employ throughout the whole of the inquiry the same lens with which it wa3 

 commenced. 



' In the Botanical Appendix to Captain King's Voyages to Australia, vol. ii, 

 p. 534:, ct seq. {aiUe 2^. 435). 



30 



