181 
observed that dehiscence invariably begins 
by the clear cut between the lip-cells, and 
then continues as a somewhat irregular 
rent through the thin walls back to the 
annulus. The material from which the 
above results were obtained was preserved in alcohol. Fresh 
plants of Adiantum Capillus-Veneris and of Pteris cretica were ob- 
tained from the greenhouse, the remainder were dried specimens 
from the herbarium. 
_ The species in which the lip-cells were observed are the fol- 
lowing: Adiantum Capillus-Veneris, Pteris cretica, Asplenium 
bulbiferum, A. Filix-femina, Aspidium Filix-mas, Polypodium 
vulgare, Scolopendrium vulgare, Woodwardia Virginica, Wood- 
sta obtusa, Camptosorus rhizophyllus, Pellea atropurpurea and 
Struthiopteris Germanica. 
Although in general the action of sporangia preserved in 
alcohol was satisfactorily studied, the results obtained remain to 
be verified from fresh specimens. If a sporangium be allowed to 
dry upon the slide, simultaneously with the appearance of the 
rent between the lips the an- 
nulus bends back until the 
ends nearly touch; then, with 
a quick jerk, it resumes its 
former position, expelling the 
spores by both movements. 
Then the annulus once more, 
but more slowly, straightens, 
generally coming to rest in 
an almost rectilinear position. 
The same phenomena may be 
observed more easily if the iit adjoining Oe 
Front view of the portionof sporangium be placed in stalk. 
the sporangium fe be- P st P 
tween the stalk and the up- glycerine and the movements somewhat 
7 aaah A tonne retarded by the pressure of the cover 
glass. As the annulus recurves the first time, the lateral walls 
of each cell, which in optical section appear like the letter 
-_U, approach each other, and the thin outer wall is pressed in so 
that the cavity of the cell is much diminished in size. At the 
Front view of ‘lip cells.” 
