344 Davis. — On the Development of the Frond of 
more mature, being provided with a firmer wall, and with 
denser cell contents. 
The first sign of germination is the formation of a thick 
hyaline wall around the spore. In the adult plant the cell- 
walls on the outside of the frond are thickened into a hyaline 
layer. This layer is developed directly from the hyaline 
coat of the spore. The formation of the hyaline coat serves 
to attach the spore to the substratum, and the cell- division 
then begins almost immediately. 
The first division of the spore takes place in a plane 
perpendicular to the substratum (Fig. 2 ), and this is followed 
soon after by another division, at right angles to the first, but 
also perpendicular to the substratum (Fig. 3). The spores 
enter the 2-celled stage about twenty-four hours after their 
ejection from the cystocarps, and then enter almost imme- 
diately into the 4-celled stage. Many examples of these two 
stages were found on the adult cystocarpic plants. The 
youngest stages were usually to be found towards the end of 
the branches of the frond, especially around those cystocarps 
whose contents had but a short time before been discharged. 
All the stages more advanced than the 4-celled condition were 
obtained from the parent cystocarpic plant. 
The cystocarpic plants, from which the later stages were 
taken, were prepared for study by fixing the plants in 
\ per cent, hot chromic acid, and were preserved finally in 
70 per cent, alcohol. Very little difficulty was experienced 
when this material was imbedded in paraffin for sectioning. 
There was but little cell-shrinkage, but some care was neces- 
sary to keep the chamber inside the frond from collapsing. 
The early stages in the segmentation of the spore were 
studied while on the adult frond. Small pieces of the frond, 
which contained the young plants, were cut off and mounted 
in 50 per cent, glycerine. By turning the piece of the frond 
over and over it was a simple matter to get both top and side 
views of the different stages. In drawing the figures, all 
sketched with the camera lucida, I have disregarded the sub- 
stratum, which in every case, except Figs. 1, 2 , and 3, was the 
