202 DIVISION IlL—-COURSE OF DEVELOPMENT OF FUNGI. 
bends over and covers the apex of the archicarp, and it is presently delimited by a 
transverse wall, forming a short nearly isodiametric cell, the ‘antheridium,’ which is 
borne on the lower part of the branch as on its stalk. The archicarp now developes 
into the sporocarp, being usually divided by a transverse wall into two cells, an upper 
which becomes the solitary ascus and subsequently produces eight spores, and a lower 
which as a stalk-cell bears the ascus. Tulasne has found two asci in a sporocarp 
as a very rare and individual exception; they were probably caused by the formation 
of ‘two transverse divisions in the archicarp-cell. The envelope-apparatus also 
begins to be formed at the same time as the ascus. From 7-9 tubular outgrowths 
appear close round the base of the archicarp on the hyphae which bear it and 
the antheridial branch, and grow up round it and in close contact with it and in 
close lateral contact with one another and with the antheridial branch, till they all 
meet together above its apex. Each tube then divides by one or two transverse walls, 
so that the incipient sporocarp is surrounded by an envelope formed of a single 
layer of many cells. These cells then increase in size in the surface-direction, their 
walls thicken by degrees and assume a dark brown colour, and they thus form the 
outer wall of the sporocarp. During this time they form no further divisions, but 
those nearest the substratum send out rhizoid branches which spread over the 
substratum ; and in some, but not all, species some of the cells at the apex of the 
sporocarp form a number of hairs with delicate ramifications which are described 
under the name of afpendiculae. Branches shoot out at an early period from the 
inner surface of the cells of the outer wall, which insinuate themselves between it and 
the growing archicarp, and ramify and develope into a dense parenchyma-like weft 
without interstices formed of two or three or more layers of cells according to the 
species; this weft has been termed the zzmer wall of the sporocarp and compared 
from its origin and arrangement with the paraphyses of more highly differentiated 
sporocarps. With these formations the sporocarp in its envelope is complete in 
all its parts, and they are followed by further considerable increase in size only, 
which in the end chiefly affects the ascus and leads to a partial displacement of 
the cells of the inner wall. The antheridial branch separates from the archicarp 
when the branches begin to be formed from the inner wall; it takes part with less 
increase in size of its parts and less considerable change of shape in the formation 
of the outer wall, between the other cells of which it remains laterally enclosed. 
The development of the sporocarp of the species of Erysiphe, under which 
genus I include all the Erysipheae which do not belong to Podosphaera, agrees with 
the above description except in certain points, the chief of which only will be 
pointed out in this place; the reader is referred for further details to the account 
given in another work’. The archicarp has the form of an elongated club- 
shaped cell, curved spirally round a hooked antheridial branch. The two organs 
are surrounded and enclosed by the tubes of the envelope, which give rise, as in 
Podosphaera, to the outer wall of the sporocarp and to the inner wall which is 
much more largely developed in these species. The antheridial branch enclosed in 
the inner wall soon disappears from observation, The archicarp on the other 
hand, lying in the basal portion of the sporocarp, grows into a curved tube and 

1 Beitr. z. Morph. u. Phys. d. Pilze, III. 
