i8o Beer. — On the Development of the Spores of 
stage before passing on to the second division. The spore-mother-cells do 
not divide simultaneously, but all stages of division can be found in one 
sporangium. A mother-cell with its nucleus in the prophases of the first 
division not uncommonly occurs side by side with one which has com- 
pleted its second division and has already developed the tetrad- (special- 
mother-cell) walls. In Botrychium Cardiff found that the cells in the 
same ‘ block ’ are always in the same stage, but in Helminthostachys the 
separation of the mother-cells has, apparently, been more complete before 
they enter upon the maiotic divisions, so that they have reached greater 
independence from one another than is the case in Botrychium. 
Bower found that a considerable proportion of sporogenous cells 
became disorganized without undergoing division. In Botrychium Cardiff 
found no such disorganization to occur, and my preparations of Helmintho- 
stachys are quite in accordance with his observations and show no abortion 
of mother-cells. When the two divisions of the mother-cell have been 
completed the four cells of the tetrad are enveloped by the tetrad-wall 
(special-mother-cell wall) (Fig. 18). 
This membrane is very delicate and in this respect forms a striking 
contrast to the conspicuous tetrad-walls of nearly all the other plants that 
I have examined (e. g. Riccia , Anthoceros , Lycopodiaceae, Osmunda &c.). 
It gives the pectic reactions very clearly, whilst several times I obtained 
a rather faint violet-pink reaction with calcium-chloride-iodine solution. 
For some unexplained reason the calcium-chloride-iodine solution does 
not always produce the same result; the tetrad-wall in some cases 
colouring violet-pink, in others yellow. 
While we may, therefore, conclude with certainty that this wall contains 
pectose, we must leave it undecided whether or not this substance is 
accompanied by cellulose 1 . The young spore-membrane colours, although 
rather faintly, with bismarck-brown, methylene blue, and similar dyes, and 
appears to be more or less cuticularized from a very early stage. It is 
a new formation and is not derived from the transformation of the special- 
mother-cell wall, which can still be recognized outside the spore-membrane 
(Fig. 6). In the meanwhile the disorganization of the tapetal walls has 
become complete, whilst the tapetal cytoplasm, which now forms a sort of 
plasmodium around the sporogenous cells (Fig. i6),has increased consider- 
ably in amount. . The numerous nuclei which it contains still tend to be 
aggregated in groups. 
We now find the plasmodial envelope sending finger-like processes into 
the cavity of the sporangium between the separated sporogenous cells. 
These cytoplasmic processes spread further and further between the sporo- 
genous cells, branching and anastomosing with one another and separating 
1 No other cellulose reaction, but only the inconstant appearance of the violet-pink colour with 
calcium-chloride-iodine, was given by these walls. 
