590 
MR. H. M. WARD OR THE MORPHOLOGY AND THE 
and allowed to roll over in fluid under the microscope, the form and arrangement are 
found to be somewhat as sketched in fig. 12 (Plate 43), where a represents the view 
from below, b that from the side, and c an end elevation of the structure. The cell A, 
in fact, is becoming gradually enfolded by the layer of cells derived from B, a process 
which results, at a later period (Plate 43, fig. 17) in the almost complete tucking in 
of the “ core ” as the centre of a subgdobular mass of cells. 
As this process of “ invagination by epiboly ” (as it would be termed in the case of 
an embryo) goes on, the “core ” has been more slowly cut up into cells—at first by 
walls perpendicular to its long axis, and then by septa in other planes at right angles 
—and the sub-globular body thus produced lies with the open part towards the 
epidermis. 
After this period, two events occur: 1st, the cells of the “core,” possessing very 
thin walls, acquire a different aspect from those of the outer shell; their finely 
granular protoplasm makes them appear denser and more opaque, shining through the 
latter until this becomes too thick to be transparent; 2nd, the open part of the 
growing perithecium becomes closed over, and the internal structures can no longer 
be made out without the aid of actual sections. At this point my observations have 
failed to decide which of two possible modes of growth take place : Is the covering 
in of the “ core ” completed simply by the extension and closing in of the edges of the 
outer layer ; or are cells, cut off from the “ core ” below, intercalated, so to speak, into 
the open gap ? One is led to expect by analogy that the former process takes place, 
but some events lead to the suspicion that such may not be the case. 
At the stage corresponding to fig. 19 (Plate 43), the young perithecium appears 
almost opaque, very little light passing through the dark-coloured and thick outer 
walls; from below, however, the larger cells composing the “ core ” can be readily seen 
in the optical section, shining by means of their dense, fine-grained contents through 
the shell. In the next stages, the “ core ” can only be seen dimly through the outer 
envelope (Plate 44, fig. 20), even after treatment with reagents, or, as in figs. 21 and 
22, after cutting or tearing off some of the outer cells. 
Nothing but a fortunate vertical section through the young fruit at or near this 
stage will decide finally whether the lower side is covered in by the meeting of the 
outer shell edges, or by partial “ delamination ” from the lower side of the “ core,” and 
this I have not succeeded in obtaining. The thick, dark outer wadis have now become 
so opaque, that optical sections fail to determine the course of events; and treatment 
with reagents does not afford evidence sufficiently satisfactory to decide the questions, 
since it seems impossible to remove the colouring matter. Potassic hydrate or weak 
acids do, it is true, render the structures a little more translucent after some time; 
but even the extreme resort of heating in weak chromic acid has only yielded partial 
results, and with this slight information on the point I have reluctantly been 
compelled to content myself for the present. A comparison of figs. 17 to 21 certainly 
suggests that the process of envelopment is completed by the outer layer of cells 
