241 
of Pilularia globulifera , L, 
presence of such cells in the antheridia of Isoetes and Sela- 
ginella , and I called attention to the same fact in Salvinia x . 
In • the study of the development of the spermatozoids 
chromic acid was used as a fixing medium, and the prepara- 
tions were stained with haematoxylin. After removing the 
prothallium from the spore, it may be carefully crushed, and 
the sperm- cells thus separated. The nuclei are relatively 
small, but contain much chromatin, so that they color very 
intensely. The development differs in no wise from that of 
other plants studied by me 2 . 
The nucleus becomes contracted on one side so as to appear 
somewhat crescent-shaped (PI. XIII, Fig. 17). It rapidly elon- 
gates, becoming at the same time thinner and more homo- 
geneous in appearance. As it elongates it winds about the 
cell close to the wall in the form of a delicate spiral band, 
having about two complete coils (PI. XIII, Figs. 19, 20). It 
occupies but a small part of the cell, the greater part being 
taken up with central contents, including numerous relatively 
large starch-granules. The cilia appear to originate from the 
peripheral cytoplasm, as in other forms. The sperm-cells 
are still clothed with a delicate membrane at the time they 
are expelled from the antheridium, but this is soon completely 
dissolved and the spermatozoids escape. These are very 
small, and coiled in a nearly flat spiral about the upper part of 
the vesicle, which is derived from the central part of the 
mother-cell, and contains the starch-granules which occupied 
that position in the sperm-cell. On killing the spermatozoid 
with an iodine solution the body becomes deeply colored, 
and the cilia are then plainly seen (PL XIII, Fig. 21). They are 
numerous, and relatively long and very delicate. Arcangeli 3 
states that there are but two cilia, but how he could have 
failed to see the others is hard to understand, as they are very 
easily demonstrated. The vesicle is very large, and becomes 
still more so by the absorption of water. Besides the starch- 
1 Campbell, in Berichte der Deutschen botanischen Gesellschaft, 1887, p. 125. 
2 Campbell, 1 . c., p. 120. 
3 1. c., p. 340. 
