200 BOTANICAL GAZETTE [MARCH 
5. In Zamia and Ceratozamia the sporangia of a sorus are some- 
times free only half their length. 
6. One strobilus of Zamia floridana had two to forty-eight spo- 
rangia on its different sporophylls, and some sporophylls in which the 
middle region was entirely covered. 
7. Strobili of Zamia floridana received July 25 showed in tangential 
sections three or four developing sporangia “ipen. either flank of the 
sporophyll, the youngest upon the margin. 
8. The archesporium is a single hypodermal cell which usually 
divides first anticlinally, followed by periclinal divisions; the outer 
plate of four cells developing the wall layers, the inner plate the 
sporogenous tissue. 
g. The wall of the mature microsporangium is composed of four 
to seven layers of cells, the cells of the two layers next the tapetum 
being tabular. The apex of the sporangium consists of thick-walled 
cells and beneath it there are isodiametric, thick-walled cells. Ex- 
tending from the apex on either side of the line of dehiscence there 
is a band of thicker-walled cells, which suggests the structure of the 
sporangium of Angiopteris. 
to. Beneath the line of dehiscence there is a plate of cells extending 
toward the center of the sporangium, which contain crystals; and 
in Zamia these cells seem to degenerate as the sporangium breaks. 
11. Stomata occur on the microsporangium, the guard cells being 
deeply sunken and thick-walled. 
12. The tapetum is derived from sporogenous tissue, at least in 
part, and the sporogenous cells at the base of the sporangium function 
as tapetal cells, which may project into the sporangial chamber. 
Sometimes, at least, the tapetal nuclei divide mitotically, for spindles 
were seen; and there are often two nuclei to a cell. The tapetum 
remains a distinct layer up to the tetrad stage. 
13. There is some additional sterilization of sporogenous tissue 
in the sporangium. 
14. The divisions of the spore mother cells conform to the de- 
scriptions of JuURANYI and Treus. The reduced number of chro- 
mosomes in Ceratozamia and Zamia is twelve. 
15. The output of spores per sporangium for Zamia floridana is 
500-600, for Ceratozamia mexicana 8,000, and for Encephalartos 
