Big? gi Some Notes on Azolla. © [ZOE 
In the macrosporangium but eight spore mother cells are produced, 
while in the microsporangium there are sixteen. In both cases,each 
spore mother cell divides into four, in the usual way; but whereas all 
of these develop more or less perfectly in the microsporangium, only 
one comes to maturity in the macrosporangium, and develops into 
the single large spore that fills its cavity. 
Shortly before maturity the protoplasmic matter filling the micro- 
sporangium separates into several masses (massulae) each of which 
encloses a number of spores. The substance of the mature massulz 
has a peculiar foamy appearance, and looks almost like a cellular tis- 
sue, but examination shows that it is only hardened protoplastic mat- 
ter,.and that the peculiar cellular appearance is caused by vacuoles 
in it. In stained sections of the nearly ripe sporangium, the nuclei 
of the disorganized tapetal cells can still be seen lying in the spaces 
between the massulz, and are evidently concerned in the formation 
of the glochidia, curious anchor-like outgrowths of the massule. , 
In the macrosporangium the protoplasmic matter surrounding the 
spore is used to build up the curious epispore and appendages. The 
epispore in Azolla filiculoides is composed of a substance very similar 
to that of the massulz. It is provided with prominent irregular 
knobs that have attached to them numerous fine threads. The up- 
_per part of the spore is crowned with three pear-shaped masses: of 
the same substance as the epispore. The ripe macrospore fills the 
sporangium so completely, and the latter fits so closely into the in- 
dusium, that its wall is so compressed as to be only discernible after 
close scrutiny. 
The sporangia are set free by the decay of the indusium, but this 
_decay is only partial in the case of the macrosporangium, and the 
upper part of the indusium becomes hard and dark-colored, and per- 
sists as a little cap, covering the top of the spore, whose base finally 
becomes entirely free by the decay of the sporangium wall. As the 
massulz escape from the microsporangium, by the complete disor- 
ganization of its wall, the glochidia stand out from them and by 
their hooked ends become fastened to the threads that cover the 
prominences on the surface of the macrospore, and often the massu- 
lz are so numerous as to completely hide the lower part of the ma- 
crospore. This is obviously a great assistance in fertilization, as the 
germinating microspores are thus brought close to the macrospore. 
In order to study the germination of the spores, sections must be 
