110 



STRUCTURAL BOTANY 



Each lobe of the anther consists of two compartments, 

 called the pollen-sacs, so that there are four of these 

 pollen-sacs altogether, running lengthways of the anther, 

 parallel to the connective. Their arrangement, as seen 

 in transverse section, is shown in Fig. 39. When ripe, 

 each pollen-sac contains an immense number of isolated 

 cells, the pollen - grains, which are set free by the 



A. 



p.m.c. 



FIG. 39. A, Transverse section through a young anther of 

 Wallflower, at the stage when the pollen mother-cells are 

 dividing. Observe the four pollen-sacs and the connective. 

 v.b, vascular bundle of connective ; /, hypodermal layer, 

 which will become the fibrous layer ; t, tape turn of 

 radially elongated cells ; p.m.c, mass of pollen mother- 

 cells, derived from arcnesporium of the pollen - sac. 

 Magnified 110. B, Three pollen mother-cells from a 

 pollen-sac in A, showing three stages of division. 

 Magnified about 450. (R. S.) (Cf. Fig. 10, st, p. 20.) 



bursting or dehiscence of the anther. The anther 

 bursts by two longitudinal cracks, coinciding with the 

 partition between the two pollen-sacs of each lobe 

 of the anther (see Fig. 40). 



The outer wall of the sacs is ruptured along this 



