THE STAMEN 201 



Put on a high power and make the following 

 observations : 



1. The wall of the anther is composed of 



(a.) A layer of epidermis, with an external cuticle : 

 within this is 



(&.) A layer of cells with a fibrous thickening of 

 the cell walls. 



(c.) Immediately within (b) will be seen a narrow 

 highly refractive band, consisting of the remnants of 

 two transitory layers of cells, the inner of which was 

 the tapetum : this is almost completely disorganized ; 

 the outer of the two layers, which abuts on the fibrous 

 layer, is less completely disorganized, and may be seen 

 as an almost continuous layer of thin- walled cells, even 

 in almost mature anthers. Note also that the wall of 

 the anther is thinnest, and its construction most simple 

 at the part most remote from the connective, i.e. where 

 the septum of each lobe meets the wall of the anther, 

 while nearer to the connective it becomes thicker. 



2. At the point where the septum meets the wall of 

 the anther the cells are smaller, and of rounded form, 

 owing to the presence of intercellular spaces between 

 them, and the inner layer is not spirally thickened : 

 this is the line of dehiscence of the anther, and the 

 lax character of the tissue at this point helps to bring 

 about the rupture. 



3. The pollen-grains or microspores, which are 

 almost spherical, with smooth walls and granular 

 protoplasmic contents, in which may be made out, with 

 difficulty, two nuclei. 



Treat fresh pollen from a full-blown flower with a solution of 

 methyl-green in 1 per cent, acetic acid, and mount in dilute 



