Beer . — On the Development of the Spores of Ricci a glauc a. 287 
mucilage lies in the fact that whilst the secondary thickening layer of the 
mother-cell walls gives both cellulose and pectose reactions, I have been 
unable to demonstrate the presence of cellulose in the mucilage. 
It must, therefore, remain uncertain for the present to what extent the 
mucilage in the sporangium possesses a nutritive value. 
By the time that the second spore-wall has become differentiated into 
the two sets of lamellae (with the dark layer separating them from one 
another) the mucilage has become very scanty, and soon after it entirely 
disappears. 
Summary. 
1. Fertilization of the egg-cell of Riccia glanca corresponds essentially 
with Garber’s description of this process in Riccia ( Ricciocarpus ) natans . 
2. The spore-mother-cells are at first separated from one another by 
extremely delicate membranes, which stain deeply with bismarck-brown 
but in which no cellulose could be demonstrated. 
3. Upon these primary spore-mother-cell walls secondary and, later, 
tertiary thickening layers are deposited. Both these layers give pectose- 
cellulose reactions. 
4. The protoplast, surrounded by the tertiary thickening layer, now 
rounds itself off. The secondary thickening layer, which becomes more or 
less mucilaginous, sometimes separates completely from the primary wall 
and then forms an external envelope to the mother-cell, whilst at other 
times it still remains partly adherent to the primary wall, and in that case 
it becomes drawn out into strands of mucilage bridging over the space 
between primary wall and tertiary thickening layer. The latter condition 
corresponds to Leitgeb’s description of this stage, but he erroneously 
interpreted the mucilage-strands as nutritive material passing into the 
mother-cell. 
5. In Riccia glauca no demonstrable nutritive material was found 
between the isolated mother-cells such as Garber and Lewis have described 
in the case of Riccia ( Ricciocarpus ) natans. 
6 . The resting nucleus of the spore-mother-cell contains a large, deep- 
staining nucleolus and a number of delicate linin fibres. No non-nucleolated, 
reticular resting nucleus, as described by Lewis in Riccia ( Ricciocarpus ) 
natans and R. crystallina , was found in Riccia glanca. 
7. The nucleolus of the nucleus of Riccia glanca appears to be 
a compound structure consisting of a number of deeply chromatic masses 
or granules embedded in a matrix which stains only faintly. 
8. A long and well-marked spirem-thread occurs in the prophase of 
the division of the spore-mother-cell. This differs radically from the short 
thread described and figured by Lewis in Riccia crystallina. 
