182 DopGEeE: METHODS OF CULTURE OF ASCOBOLACEAE 
the bottom, within the medium itself or on the surface. Whena 
very hard agar is used, as described under spore germination, the 
mycelium from the germinated spores divides into two portions, 
one growing on the surface, the other along the very bottom. On 
focusing down through the medium the two planes of growth are 
seen to be very sharply defined. The older mycelium does not 
show the planes of separation as does the mycelium formed during 
the first few days. Another interesting feature in this connection 
is the vertical distribution of the ascocarps. In some cases all of 
the ascogonia were formed deep down in the medium and in direct 
contact with the bottom of the dish. Again they would form on 
the very surface of the medium or be distributed irregularly as 
regards depth. The amount of light and its direction, the tem- 
perature of the room, and the depth of the medium in the dish 
are apparently the determining factors in this respect. 
The apothecium takes its origin in a well marked archicarp, 
which arises as a branch of a mycelial hypha and immediately 
bends sharply on itself. As growth proceeds its diameter increases 
to such an extent that it can be readily distinguished from ordinary 
vegetative branches (FIG. 50). A septum is formed a few microns 
from the parent hypha, and the distal part (FIG. 51) begins to curve 
at the tipand to form a spiral (FIG. 52) which ultimately consists of 
two or three complete turns (FIG. 53). This spiral may be formed 
on the same side of the hypha where it originated, or the branch 
may curve over or under the hypha and form the spiral on the 
opposite side. The coil continues to grow and thicken and soon 
becomes septate. Its tip becomes somewhat long and tapering; 
and on analogy with the carpogonia of the lichens may be regarded 
as a trichogyne. We can distinguish three regions in this initial 
organ (FIG. 54): the stalk (a) consisting of two or three cells; 
these, however, are not sharply distinguished from (b) one of the 
two or three larger central cells, which later becomes the ascogenous ~ 
cells. The remaining outer portion of the spiral (c), which I shall 
call the trichogyne, is made up of three or four cells which gradu- 
ally decrease in diameter and end rather abruptly (FIG. 53): At 
this time the cells of the coil are not inclosed by investing hyphae 
A great many archicarps can be found in the stage of development 
shown in FIG. 53, and this may indicate that a short resting period 
