27 6 Beer. —On the Development of the Spores of Riccia glanca . 
of the egg-cell is far less than is usually figured, and in this point I am again 
in agreement with Garber’s statements. The first division of the fertilized 
egg-cell is usually obliquely transverse (Fig. 32). The succeeding divisions 
have been so frequently described that I need not recapitulate them here. 
They result in a mass of sporogenous tissue surrounded by a single layer of 
sterile wall-cells, the whole being enclosed within a two-layered calyptra. 
The young spore-mother-cells are at first separated from one another by 
extremely delicate membranes (Fig. 29). These stain, often deeply, with 
bismarck brown, but I am unable to get a decided reaction in them with 
ruthenium red, whilst with calcium-chloride-iodine and chlor-zinc-iodine 
they colour yellow but show no signs of containing cellulose. 
The cell contains a quantity of starch which is especially abundant 
round the nucleus. Upon the primary walls which separate the spore- 
mother-cells from one another a secondary and, later, a tertiary thickening 
layer is deposited (PL XXI, Fig. 5). Both layers give the reaction of 
cellulose as well as those of pectose, but the tertiary thickening layer 
(viz. the one in immediate juxtaposition with the protoplast) stains the 
more deeply with pectic reagents. 
The protoplast surrounded by the tertiary thickening layer now rounds 
itself off and becomes separated from the primary mother-cell membrane. 
The secondary thickening layer, which has become more or less mucilaginous 
in consistency, sometimes separates completely from the primary walls and 
then forms a well defined layer surrounding the protoplast (Figs. 5j 9> 3 1 )- 
At other times, on the contrary, it remains partly adherent to the primary 
wall and in that case it becomes drawn out into a number of strands 
bridging over the gap between the rounded protoplast and the primary 
wall. The latter condition is represented in Fig. 6, and it will be observed 
that my drawing closely resembles Leitgeb’s Fig. 3, Taf. II. Leitgeb, 
however, believed that the space between the primary wail and the proto- 
plast was occupied by a homogeneous mucilage, and that the strands of 
material which both he and I have figured are composed of food-materials 
diffusing in from the outside. In my preparations it is quite certain that 
no homogeneous mucilage occupies the space between protoplast and 
primary wall ; moreover the strands of material stretching across this space 
give cellulose and pectose reactions exactly corresponding with those 
obtained in the secondary thickening layer (e. g. of Fig. 5 where the cells 
are still partly united). 
It should be mentioned that the condition represented in Fig. 6 is no 
doubt somewhat exaggerated by the reagents used. The measurement of 
the spore-mother-cells shown in Figs. 30 and 9 gave an average diameter of 
about 46 ju, whilst that of the cells in the sporangia from which Fig. 6 was 
drawn was only 40 /x. I believe, therefore, that the effect is somewhat 
heightened by the reagents employed, but I see no reason to conclude that 
