I2 5 
Steil. — A p agamy in Nephrodium hirtipes, Hk. 
such instances were observed in any of my preparations. Whether such 
spores whose nuclei do not possess the normal number of chromosomes have 
the power to germinate has not been determined. 
The formation of more than four spores from a single spore mother-cell 
has been reported in Angiosperms by various investigators. Wille (1886) 
gives a summary of the early literature of the subject and reports also his 
own discoveries. Strasburger (1892) and Juel (1897) found that the super- 
numerary pollen grains of Hemerocallis fidva are produced by the forma- 
tion of cells whose nuclei originate from chromosomes which fail to pass to 
either pole during the division of the spore mother-cell. Fullmer (1899) 
observed in the same species that occasionally some of the nuclei of the 
spore-tetrads divide, and that as a result of these divisions additional micro- 
spores are produced. Miss Lyon (1898) reported that in Euphorbia corollata 
sometimes five or six microspores are produced in place of the usual four 
spores of a tetrad. No explanation is given for the presence of the super- 
numerary spores in this plant. So far as I know, the formation of more 
than four spores from a spore mother-cell has not previously been described 
in any of the Bryophytes or Pteridophytes. 
Discussion. 
In my preliminary note (1915 b) I described cell and nuclear fusions in 
the sporangia of Nephrodium hirtipes similar to those described by Miss 
Allen (1911) in Aspidium falcatum . Since sporangia of Nephrodium 
hirtipes were found containing eight sporogenous cells whose nuclei in some 
cases were in prophases and in other cases in metaphases, it seemed that the 
completion of the divisions must result in the formation of sixteen sporo- 
genous cells in each sporangium. In older sporangia figures were found 
which seemed to show that these sixteen cells were fusing in pairs. The 
presence of thirty-two spores in each sporangium, evidently produced by the 
division of eight spore mother-cells, apparently confirmed this conclusion. 
However, a later and more extended study of additional preparations, which 
contained an abundance of division figures, has shown that the divisions 
first initiated at the stage of the eight sporogenous cells arc never or very 
rarely completed ; that these incomplete divisions result in irregular cell 
and nuclear forms, as well as in the partial division of the cells by cell-plates 
or walls, which were first interpreted as evidences of cell fusion ; and that 
the result of these incomplete divisions, as indicated in what precedes, is 
a doubling of the number of chromosomes in each of the eight cells which 
then proceed to function as spore mother- cells. A later examination of my 
older preparations shows, as a matter of fact, that they contain very few 
earlier stages in incomplete nuclear and cell division, and hence the most 
important evidence on the history of the sporogenous cells was not at first 
obtained. 
