THE ARCHESPORIUM 107 
found to be the case in many of the Pteridophytes. But it was not 
‘sufficiently recognised that between the two lies all the difference between 
‘stratified and imperfectly stratified meristems. This point was brought 
forward in 1896, in the proposition that “the study of the sporangia or 
synangia of a plant should be carried out in the light of a knowledge 
‘of the segmentation of its apical meristems,” and the generalisation was 
laid down that ‘‘where the apical meristems are distinctly stratified, the 
‘structure of the young sporangium is stratified also: in those plants where 
there is a non-stratified structure, with one or more initial cells. and 
‘frequent periclinal division of superficial cells near the apex of stem, leaf, 
or root, there the structure of the young sporangium is not distinctly 
stratified.” Such exceptions to the hypodermal position of the arche- 
sporium as have been found among the Pteridophytes all fall under this 
generalisation, and it may be added as a corollary that in all Vascular 
Cryptogams investigated, the sporogenous tissue is ultimately referable to 
the segmentation of a superficial cell or cells. This has been since 
noted by Wilson Smith,? who has accordingly suggested that the term 
“archesporium ” should be extended to these also, and he gives the definition 
as follows: “The cell, or group of cells, whether superficial or hypodermal, 
to which in a last analysis all the sporogenous portion of a sporangium 
‘can be traced, ought to be called the archesporium.” 
The use of the term “archesporium” has been discussed afresh by 
‘Goebel in his Organography (p. 771). He first describes the case for the 
anther of an Angiosperm thus: ‘‘In each of the four angles of the anther 
a cell-row or cell-layer below the epidermis (hypodermal) divides by 
periclinal walls. Of the cells which thus arise the internal form the 
archesporium, the outer the ‘schichtzellen,’ which now divide still further 
by periclinal walls.” The archesporium is thus defined as the inner product 
of the division of the hypodermal layer; it gives rise neither to any part of 
the sporangial wall nor to the tapetum, though, since these have a common 
origin with it from the hypodermial layer, it is not clear why the latter 
should not itself be styled the archesporium. Passing on to the Pteridophyta, 
aftér noting how superficial cells give rise to the essentials of the sporangium, 
and that the details are not uniform, he proceeds (Zc, p. 774): “We 
may then designate that superficial cell or cell-layer as archesporium which 
sooner or later gives off sterile cells, while in the sporangia of Angiosperms 
the archesporium is a cell-layer lying below the epidermis, which is already 
differentiated: with this the above-noted differences in wall-structure of the 
Pteridophyta and Gymnosperms on the one hand, and of the Angiosperms 
on the other would correspond.” This passage calls for the following remarks. 
In the first place, Goebel accepts the conclusion of Wilson Smith, 
that since the sporogenous tissues of Pteridophytes are all referable in 
origin to superficial cells, therefore those cells are to be recognised as 
the archesporium. By accepting this conclusion, it may be presumed that 
1Studtes, ii, p. 8. 2 Bot. Gazette, vol. xxix., p. 323. 
