Harper —Cell- Division in Sporangia and Asci. 469 
Their surface consists of granules just like those in the mass 
of the protoplasm. A boundary line appears when they 
separate from each other and from the sporangial wall. 
They are thus completely bounded off from each other before 
a cellulose cell-wall appears, though this is formed shortly 
after their separation. 
The protoplasm cleaves simultaneously, and not by succes- 
sive bipartitions breaking into larger and then smaller 
portions. There is no deposition of slime between the 
plasma masses during the process of division. The septum 
now becomes convex upwards, due to the pressure of the 
protoplasm below. 
No cytoblast (nucleus) is present in the spores. They are 
bounded by a cellulose wall, and beneath this the protoplasm 
is covered by a primordial utricle. The oospores are formed 
in the same fashion as the swarmers. The primordial utricle 
of the sporangium and oogonium is used up in spore-formation, 
but cannot be considered as dividing to form the entire new 
primordial utricle for each spore. Pringsheim recognizes that 
Nageli’s distinction of ‘ wandstandige Zellbildung’ and free 
cell-formation is dependent entirely on the degree to which 
the sporangium is filled with protoplasm. 
Biisgen 1 investigated the sporangia of the Phycomycetes 
after Strasburger’s description of the cell-plate in the 
Phanerogams, and is evidently much influenced in his 
interpretation by Strasburger’s work. He describes the 
cleavage as occurring simultaneously by means* of cell-plates. 
These cell-plates which are formed at first break down, and 
are later reconstituted for the definitive separation of the 
spores. 
This period of disappearance of the cell-plate, as we shall 
see later, doubtless corresponds to the period of swelling 
when the spores are so closely pressed together that their 
boundaries become indistinct. The whole process is supposed 
to be analogous to full cell-formation, as described by 
Strasburger for Eranthis hiemalis . 
1 1. c. 
1 i 2 
