300 NOTICES OF THE MEETINGS [April 15, 
since the promulgation, in 1838, of the celebrated Cell-theory of 
Schwann. Admitting to the fullest extent the service which this 
theory had done in Anatomy and Physiology, the Lecturer endea- 
voured to shew that it was nevertheless infected by a fundamental 
error, which had introduced confusion into all later attempts to 
compare the vegetable with the animal tissues. This error arose 
from the circumstance that when Schwann wrote, the primordial 
utricle in the vegetable-cell was unknown. Schwann, therefore, 
who started in his comparison of Animal with Vegetable Tissues 
from the structure of Cartilage, supposed that the corpuscle of the 
cartilage cavity was homologous with the ‘‘ nucleus” of the vege- 
table cell, and that therefore all bodies in animal tissues, homo- 
logous with the cartilage corpuscles, were “nuclei.” The latter 
conclusion is a necessary result of the premises, and therefore the 
Lecturer stated that he had carefully re-examined the structure of 
Cartilage, in order to determine which of its elements corresponded 
with the primordial utricle of the plant,—the important missing 
structure of which Schwann had given no account: — working 
subsequently from Cartilage to the different tissues with which it 
may be traced into direct or indirect continuity, and thus ascer- 
taining the same point for them. 
The general result of these investigations may be thus expressed : 
—In all the animal tissues the so called nucleus (Endoplast) is the 
homologue of the primordial utricle (with nucleus and contents) (Endo- 
plast) of the Plant, the other histological elements being invariably 
modifications of the periplastic substance. 
Upon this view we find that all the discrepancies which had 
appeared to exist between the Animal and Vegetable Structures 
disappear, and it becomes easy to trace the absolute identity of 
plan in the two, —the differences between them being produced 
merely by the nature and form of the deposits in, or modifications 
of, the periplastic substance. 
Thus in the Plant, the Endoplast of the young tissue becomes 
a “primordial utricle,” in which a central mass, the “nucleus, ” 
may or may not arise; persisting for a longer or for a shorter 
time, it may grow, divide and subdivide, but it never (?) becomes 
metamorphosed into any kind of tissue. 
The periplastic substance follows to some extent the changes of 
the endoplast, inasmuch as it generally, though not always, grows 
in when the latter has divided, so as to separate the two newly 
formed portions from one another; but it must be carefully borne 
in mind, though it is a point which has been greatly overlooked, 
that it undergoes its own peculiar metamorphoses quite indepen- 
dently of the endoplast.—This the Lecturer illustrated by the 
striking case of the Sphagnum leaf,in which the peculiarly thick- 
ened cells can be shewn to acquire their thickening fibre after the 
total disappearance of the primordial utricle, — and he further quoted 
M. von Mohl’s observations as to the early disappearance of the pri- 
