420 BOTANICAL GAZETTE [NOVEMBER 
IG. —Primary microsporogenous cells na to degenerate; 
anticlinal division preceded usual periclinal in archespo 
IG. 51.—Primary microsporogenous cell in savsee degeneration. 
Fic. 52.—First division in normal primary microsporogenous ce 
Fic - 53 .—Degeneration restricted to a single cell (in pend t section 
of early: microsporogenous tissue. 
1G. 54.—Degeneration of isolated cells in later microsporogenous tissue. 
IG. 55.—Advanced degeneration of entire mass ef microsporogenous 
cells; wall cells are also involved. 
Fic. 56.—Same at a later stage of development; wall cells nearly normal. 
Fic. 57.—Portion of normal anther at synapsis of microspore mother 
Fro. 58.—Same stage, with premature degeneration of tapetum 
IG. 59.—Same stage, with microsporogenous tissue enntphevely dis- ~ 
organized; middle wall layer and tapetum greatly enlarged. 
1G. 60.—Diakinesis stage of heterotypic mitosis in normal microspore 
mother cell, showing 32 pairs of chromosomes, the haploid number; recon- 
structed from 2 sections 
TSS, CES section of loculus of collapsed anther, in which degen- 
erating ‘sporogenous tissue has just completed reduction; tapetum shows 
variety of nuclear situations, and is still functional. 
1G. 62.—Tetrad of microspores in various stages of degeneration. 
Fic. 63.—Probably normal disorganization of tapéetum at a time when the 
microspores are well differentiated, although apparently beginning to degener- 
ate. 
Fic. 64.—Apparently normal microspore. 
Fic. 65.—Microspore degenerating. 
Fic. 66.—Microspore with walls completely differentiated, in advanced 
degeneration. 
1G. 67.—Apparently nearly normal pollen grain with generative cell 
organized. 
Fic. 68.—Same, showing beginning of hypertrophy and starch accumula- 
tion 
Fis. 69.—Hypertrophied pollen grain, packed with large starch grains. 
Fic. 70.—Hypertrophied pollen A with contents beginning to dis- 
— penetrated by a fungus hyp 
i wha .—Hypertrophied pollen grain with contents in advanced dis- 
Sees nieaticn 
Fic. 72. Sane with beginning of pollen tube formatio 
Fic. 73.—Hypertrophied pollen eae with contents © dlasernien to 
homogenenus mass an beginning to colla 
G. 74.—Portion of hypertrophied olleg grain with well developed pollen 
tube; gr tasted nuclei still in grain. 
Fie - 75.—Hypertrophied pollen grain with long pollen tube into which 
remains “of disorganized nuclei have migrated. 
