5oS 
Lang. — On Apospory in 
into the thallus, the material for the growth of which is pro- 
vided by its chlorophyll-containing cells. The zygote en- 
closed in the venter of the archegonium is at first wholly 
dependent on the gametophyte, and the sporogonium developed 
from it never becomes free from the latter. 
Similarly, with regard to the explanation of such a deviation 
from the ordinary life-cycle as apospory, both the character 
of the cells, from which the development proceeds, and the 
nature of the conditions, to which they are exposed during 
development, require consideration. As regards the former 
point, it has been shown above that certain cells or groups of 
cells of the sporogonial wall remain alive while others die and 
disintegrate. The living cells thus become to some degree 
isolated in position and, as may fairly be assumed, physio- 
logically also. The cells of the cut ends, which were seen to 
commence growth earlier, are partially isolated by the section 
through the sporogonium. These cells of the wall have also 
been seen to be the least specialized in the sporogonium, and 
they are capable of the continued manufacture of organic 
material. Whatever the changes involved in the reconstitution 
of these cells may be, all these facts point to there being 
a general physiological distinction between them and the 
other tissues of the sporogonium. In Anthoceros , as in the 
cases of apospory among Ferns, the sporogenous tissue itself, 
if it is distinguishable, does not take part in the origin of the 
new growths. The only apparent exception to this, as a 
general rule, is in the case of the mosses, in which Pringsheim 
points out that the zone of the seta, from which protonemal 
filaments arise, corresponds to that zone in the capsule be- 
tween columella and wall in which the archesporium lies. 
But the whole of the seta is sterile tissue and there is no 
evidence that archesporial cells themselves give rise to new 
growths. On the other hand, Stahl’s observation, that apo- 
spory could be induced in the cells of the capsule-wall, shows 
clearly that there is no necessary connexion in the Mosses, 
between the archesporial region and apospory. In Mosses, 
as in Anthoceros , the growth starts from little-specialized 
