90 AT-DRIDGEON POLLFN. 



to introduce, would be the last to appropriate the discoveries 

 that have been ascribed to them ; and, on the other hand, it 

 is easy to comprehend how a vague recollection of the influ- 

 ence of acids upon the pollen, may have led some gentlemen, 

 present at the meeting of the Association, to have confounded 

 my discoveries with theirs. 



To proceed to the analysis of Fritzche's valuable memoir, 

 a chapter, purporting to treat of the structure of the pollen 

 in general, is principally devoted to an examination of the 

 organ called globule in Char a. He considers this to be iden- 

 tical with the anther of higher plants : his description of the 

 different portions of this organ are exceedingly minute, but, 

 without the accompanying plates, it would be useless to re- 

 peat them here. 



The next chapter treats of the contents of the. pollen. 

 This, which has received the name of Jhvilla, is a mixture of 

 different chemical substances, which can be severally recog- 

 nised by reagents. We are easily capable of perceiving three 

 classes of substances — namely, mucus, oil, and starch ; the 

 last we can alone ascertain with sufficient exactness; the first 

 being a mixture of different substances, whose chemical union 

 we cannot distinguish with our present instruments ; and the 

 second most probably exists as a mixture of different oily 

 bodies. 



The muais of the fovilla, is a colourless substance, which 

 in water swells very much, without, as it would appear, being 

 permitted to dissolve itself therein ; it acquires, through solu- 

 tion of iodine, an intense yellow-brown colour; it becomes 

 coagulated by acids, and either dissolves in concentrated 

 sulphuric acid, or being soaked in it, becomes transformed 

 into a very transparent gelatinous mass. The property of 

 swelling in water, which it participates with Bassarine, is the 

 cause of the bursting of the pollen-grains, when they come 

 into contact with water; the membranous integument becomes 

 at first distended, but when the maximum of its elasticity is 

 attained, it very often cannot resist the force with which the 

 mucus still sucks in more water, and then it bursts, either at 



