222 BOTANICAL GAZETTE [october 
such cavities. In fig. 2, from another portion of the same aetha- 
lium, parts of several lacunae are shown, and their relative size 
and distribution is thus partially indicated. 
In addition to the solid particles and solutions thrown out, 
the protoplasm excretes over its whole surface a thin fragile 
membrane, in which the crystals of lime are frequently partly 
imbedded. This membrane is by no means as thick as in the 
case of the slime molds which produce sporanges, but it appears 
very clearly in microtome sections. In most regions it is hardly 
more than a cement to hold together the lime crystals in a 
continuous film. In other regions, where these are less abun- 
dant, it appears as a very thin homogeneous membrane. It 
lines all the interprotoplasmic cavities mentioned above, as 
well as covering the peripheral portions of the protoplasm. 
It: is always next to the protoplasm itself. I have never 
found crystals or other solid excreta between it and the plasma 
membrane. 
At a stage when cleavage is just beginning, such af tit 
shown in jig. 1, the nuclei are generally in the resting condition, 
and are distributed rather unevenly through the cytoplasmic 
mass. Frequently they appear aggregated in rather dense 
Sroups in certain regions, while in adjacent regions of the bees . 
plasm they are less numerous. Spore development now begits : 
with the formation of cleavage furrows, which usually arise first _ 
on the external surface of the entire aethalium and cut down @ 
all angles into the homogeneous protoplasm. These furrows a 
very narrow and sharp in some cases, and quite widely opens’ — 
in others ( fg, rT). This latter condition may be due, at leas - 
partly, toa slight shrinkage in fixation. Very commonly 6! 
are curved and forked so as to cut off a superficial layer “ fi 
ments. Almost simultaneously with the formation of these ae 
FOws on the surface of the entire aethalium, similar furrows #° : 
formed on the surfaces of the lacunae of the contracted ahs 
plasmic reticulum as described above. These surfaces, of mee 
are in reality external surfaces of the protoplasm, and . 
formation of cleavage furrows from them is not in any Sense ~ 
