204 Hartog. — Recent Researches 
arrest of the apical growth of a hypha, while protoplasm 
continues to stream in from the base, usually determining an 
ovoid enlargement ; at first the thick protoplasm of the 
sporangial part of the hypha passes gradually into the thinner 
investment of the basal part ; but soon the contrast is sudden 
and sharp. Then at this junction the granules disappear or 
migrate from the protoplasm so as to form a longish ring of 
hyaloplasma which grows at its inner circumference to finally 
form a transverse disk extending across the hypha from wall 
to wall, sharply bounded towards the basal hypha but on 
the sporangial side gradually passing into the granular 
protoplasm. 
In about half-a-minute the transverse septum appears 
(simultaneously) at the base of the disk, at first pale (‘ verwas- 
chen’), soon sharp-contoured. In favourable cases we may 
see that a rather broad basal section of the disk of hyalo- 
plasma assumes a higher refraction ; this gradually thins off 
and becomes more clearly defined and finally condenses 
(‘ sich verdichtet ’) into the septum ; which is clearly not 
formed from a granular cell-plate as Strasburger states. 
Before this, however, a number of Pringsheim’s cellulin cor- 
puscles had accumulated about the limiting area, and fell, 
by the appearance of the hyaloplasma disk, into an upper and 
a lower group. As the upper group disappear on the comple- 
tion of the hyaloplasma disk, Rothert thinks it probable that 
the granules, consisting of a very soluble form of cellulose, 
are absorbed into the disk and by their solution afford materials 
for the septum. 
Slight modifications occur in the formation of the hyalo- 
plasma disk according to the relative fulness or emptiness of 
the sporange. 
We now come to the formation of the zoospores, and first of 
all their partial segregation, in which stage we may call them 
‘spore-origins’ (Sporen - Anlagen). We can distinguish 
between (i) full sporangia which at first contain no central 
cavity or to which class usually belong the smaller sized ones ; 
( 2 ) ordinary or normal sporangia with a fairly thick parietal 
