CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES.—EUROTIUM. 203 
divides by transverse walls into a row of several cells, from which a number of 
broadly club-shaped erect asci are formed by each cell of the row growing out 
directly into an ascus, or putting out a few short branches which terminate in asci 
and are therefore ascogenous. 
In both Erysiphe and Podosphaera the formation of the envelope is at first in 
advance of that of the asci, and is nearly finished when the asci or the cells which 
produce them are still quite small; and it is not till the last stage of the development 
that the growth of the asci advances, chiefly at the expense of the tissue immediately 

FIG. 94. Eurotium repens. A branch of the mycelium with a gonidiophore c and young archicarps as: sf sterig- 
mata. J spirally twisted archicarp 2s with the antheridial-branch and an pe-branch. C older specii with a 
larger number of lope-b hes g1 ing round the icarp ; # antheridial branch. D young sporocarps seen from. 
without. £ and F other young sp ps in optical longitudinal section. In £ the inner wall is beginning to be formed ; 
w the outer wall, / the inner wall-cells and the cells filling the space between the ascogonium and the wall. as the 
ascogonium. G ascus with spores. # ripe of E. Aspergili le isolated. 4 magn. 190 times, the rest 
of the figures 600 times. 




surrounding it. The spores are in most cases formed as soon as the asci have 
reached their full size; but in some species, as Erysiphe Galeopsidis and E. graminis, 
(Wolff), there is a pause in the development before the formation of the spores, and 
further progress only takes place under favourable conditions of temperature and 
moisture after a resting period of some duration which happens to fall in the winter- 
time; the protoplasm of the tissue of the inner wall is evidently employed to form 
the spores. 
2. The archicarp of Eurotium (Fig. 94) is produced by the gradual basi- 
petal coiling of the extremity of the upper end of a branch of the mycelium into 
