1915] BRIEFER ARTICLES 255 
ordinary prothallia, which may in their turn produce apogamous embryos. 
In all my cultures apogamous embryos have been produced in large 
numbers. From observations so far made it appears that all the pro- 
thallia may produce such embryos. Some of the young sporophytes 
have been grown to a height of several inches and are apparently normal 
in every respect. 
‘An investigation of the nuclear history of this species led to the dis- 
covery of cell and nuclear fusions in the sporangia, similar to those 
described for the first time by Miss RurH ALLEN in Aspidium falcatum, 
and not thus far described in any other fern. Nothing unusual has been 
observed in the early stages in the development of the sporangia. By 
four successive divisions 16 cells are formed from the primary sporoge- 
nous cell. These cells instead of functioning as spore mother cells, 
as do the cells of the corresponding cell generation in the sporangia of 
most of the Polypodiaceae, fuse in pairs. Sometimes the wall between 
two neighboring cells completely disappears before the fusion of the 
nuclei. Frequently only a portion of the walls disappears before the 
fusion of the nuclei is completed, but as a rule they wholly disappear 
ater. 
The 8 cells produced by the fusions just described are the ones that 
function as the spore mother cells. Heterotypic and homoeotypic 
divisions occur, forming typically 32 spores. The mature sporangium, 
however, frequently contains fewer than 32 spores. Irregularities 
occurring in sporogenesis may account for the presence of the smaller 
number of spores in a sporangium. Spore mother cells in synapsis, 
various stages in the divisions of the spore mother cells, and tetrads are 
sometimes found at the same time in a single sporangium. This is out 
of harmony with the usual course of events in fern sporangia, and it is 
possible that some of the cells in the earlier stages of development may 
fail to complete their division. Occasionally cell and nuclear fusions 
are not completed. It is highly probable that the number of spores in 
a sporangium is frequently reduced by these irregularities and abnormali- 
ties among the spore mother cells.—W. N. StE1L, University of Wisconsin, 
Madison, Wisconsin. 
