Anthoceros laevis. 
505 
long narrow cells. In the epidermal cells are small starch- 
grains ; in the other cells of the wall a considerable amount 
of starch may be present within the single large chloroplast, 
while the cells of the columella and trabeculae contain little 
or no starch. The young spores contain abundant starch. 
Thus the cells of the five inner layers of the wall are the 
least specialized of the sterile cells of the sporogonium and 
contain the greatest amount of reserve material, while the 
presence of a healthy chloroplast in them enables this supply 
to be increased. 
After cultivation on damp sand the pieces of sporogonium 
became more or less disintegrated, and many of the cells 
composing them were evidently dead or dying. Others, how- 
ever, were still healthy. Such cells occur throughout the 
wall, most commonly in the layers close to the epidermis, 
and they stand out prominently when stained with iodine 
owing to their chloroplasts containing starch. Many of these 
living cells had not divided, and only differed from the cor- 
responding cells in the uninjured sporogonium in having 
rounded themselves off somewhat from their neighbours. In 
others, however, cell-divisions had taken place. These divisions 
may commence in cells which are still covered by the epi- 
dermis (Figs. 4, 5), but the new growths develop more rapidly 
when they are on a free surface of the piece of .sporogonium. 
Thus those growths which arise from the cut surfaces at the 
ends (Fig. 1) develop first and, as the figure shows, may 
attain a considerable size while the epidermis is still intact. 
As the disintegration proceeds, however, the epidermis gets 
broken and in places stripped off, and then growths arising 
from the cells beneath, such as that shown in Fig. 3, are 
enabled to continue their development. 
In almost every case each new growth appeared to owe its 
origin to a single cell of the sporogonium (cf. Figs. 3-6). 
The divisions, which take place in the cell, are subject to 
considerable variation, but the first is usually transverse and 
often separates a lower cell, in which few or no further 
divisions occur, from an upper, which gives rise to the new 
