346 Davis . — On the Development of the Frond of 
to three cells, while the four cells directly above them (num- 
bered 4) have been divided first into eight cells by walls 
parallel to the substratum, and then each of the four upper 
cells have been divided by a perpendicular wall. 
Disregarding the thick gelatinous coat, it is probable that 
the segmented spore is about the same size as the freshly 
discharged spore. This is illustrated by the series, Figs. 1-9, 
all made under the same magnification, namely 450 diameters. 
The ripe spores themselves vary from -05 to *08 mm. in 
diameter, and one would expect a corresponding variation 
among the different stages. Up to this time there has been no 
forward growth of the young plant, and all the cell-division 
has been concerned with establishing the young plant firmly 
upon its support by means of the four small holdfasts. There 
has been nothing like that apical growth which is peculiar to 
the adult. 
Professor Debray l , in his second memoir, mentions having 
germinated the tetraspores of Chylocladia kaliformis , but he 
did not follow their development carefully. He remarks that 
they divide in an irregular manner, while preserving their 
spherical shape. In my own experience I have found the 
earlier stages (Figs. 2-7) very common and with the greatest 
symmetry of form, but, of course, with later stages there is 
much greater likelihood of irregular cell-division. I have 
found in the few examples of stages five and six (Figs. 7 and 8) 
that I have examined (for these stages are passed over quickly, 
and are consequently rarer and are also more difficult to 
manipulate), that there are sometimes slight irregularities in 
cell-division. Often some of the cells, by their more rapid 
growth, have crowded their neighbours a little out of the proper 
symmetrical arrangement. However, these irregularities were 
usually at the base of the plant, and in all cases there were 
four cap-cells at the top of the young plant. It is from these 
four cap-cells that the apical growth begins, and from them 
that the group of initial cells arises. 
1 Debray, Bull, scientif. de la France et de la Belgique, Tom xxii. p. 
4 J 5* 
