* 1905] CARDIFF—SPORANGIUM IN BOTRYCHIUM 341 
In the sporangium of Lycopodium, the sporogenous mass _ is 
divided into blocks of cells, each block apparently being the descend- 
ant of a single archesporial cell. The blocking here is evidently 
related to a multicellular archesporium. In the Botrychium spor- 
angium there occurs a blocking of the sporogenous mass that must 
have a different cause, as the archesporium is unicellular. The single 
hypodermal archesporial cell divides usually anticlinally, then peri- 
clinally (fig. r). Regular divisions then follow, as shown by jig. 2. 
At the stage shown in fig. 2 the wall is six to eight cells in 
thickness, including the tapetum; and the extremely glandular char- 
acter of the two inner layers of cells indicates that they are definitely 
set apart as tapetum. In the tapetum at this stage walls are formed 
both periclinally and anticlinally. The divisions in the sporogenous 
Mass occur with remarkable regularity. The position of the original 
walls, from stages shown in jigs. r and 2, are still perfectly apparent 
up to the spore mother-cell stage (jig. 3). At this stage the sporog- 
€nous mass has somewhat the appearance of the spermatogenous 
mass in a bryophytic antheridium, except for the size of the cells and 
the character of the nuclei. By the time the mother-cell stage is 
reached, the tapetum has become four or five cells thick, is quite 
glandular in appearance, and there is no further evidence of mitotic 
division. The sporangium wall-cells adjacent to the tapetum have 
commenced to collapse as a result of the drain upon them by the 
tapetum. 
Probably the most common and most primitive method of nour- 
ishment of mother-cells is by abortion and absorption of a portion of 
the mother-cells to form a diffuse tapetum, as in Equisetum. Another 
method is by the formation of sterilized tracts from potentially sporog- 
€nous tissue through which material may be conducted to the interior 
of the sporangium, as the trabeculae of Isoetes or the septations in 
the microsporangia of Lemna minor. 
In the sporangium of Botrychium, no sterilization of either kind 
was found, every mother-cell functioning. So far as I was able to 
determine, division up to the mother-cell stage is simultaneous 
throughout the sporogenous mass, yet the original blocks (jig. 3) 
of sporogenous cells still remain perfectly distinct. As the mother- 
cell enters upon the synapsis stage, the original walls or wall separating 
