174 Barker . — The Morphology and Development of 
(see Fig. 2 ,g). The penultimate cell thus cut off varies con- 
siderably in size at the time of formation (see Figs. 2,g; 3, b ; 
and 5), but in all cases it has dense semi-transparent slightly 
granular protoplasmic contents and practically no vacuoles. 
It is from this penultimate cell that the ‘ sporangium * of 
previous authors is developed. 
On account of its importance and position I propose to 
term it the ‘ central cell/ the older terms ‘ sporangium * and 
£ ascus 5 being, as will be seen later, erroneous. 
It soon begins to swell up, and vacuoles make their appear- 
ance, its shape during the earlier period of swelling being 
more or less reniform or bean-shaped (see Fig. 2,/z). Later 
it becomes spheroid or ovoid. 
The ascogonium consists during this period of two cells, 
viz. the central cell and a cell at its apex, which is made up 
of that portion of the organ which has taken part in the fusion 
with the antheridial branch, and is more or less comparable 
to a ‘trichogyne’ (see Fig. 2 , g, &c.). Shortly after the 
formation of the central cell, investing hyphae begin to be 
formed around it. These are developed from the hypha 
which has produced the archicarp, and arise from that part of 
it immediately below the limiting septum of the ascogonium, 
i.e. just below the central cell. 
In most cases a single hypha is produced in that region ; 
and this proceeds to grow up around the central cell, closely 
applied to it (see Fig. 11, a). It begins very quickly to put 
out lateral branches, which also clasp the central cell. The 
lateral branches, especially the earlier ones, are usually pro- 
duced in pairs, and grow in opposite directions. These, in 
their turn, produce other branches, also clasping the central 
cell ; and development in this manner continues until the cen- 
tral cell is covered on every side, except those in contact with the 
antheridial branch and ‘ trichogyne cell,’ by investing hyphae. 
The growth of these hyphae then ceases (see Fig. 11, d-d). 
In speaking of the central cell as being invested on every 
side by these hyphae, it must not be understood that the 
whole surface is completely covered by them. What is 
