154 PROGRESS OF MICROSCOPICAL SCIENCE. 
subject before the Royal Society.* This paper must be read by those 
interested in the subject, but we may quote the following passages as 
being of special interest :—“ Then, as I am spending my life not to 
illustrate the cranial morphology of this type or of that, but as 
digging down to find one common root, I have made an incipient 
attempt at showing what is common to the whole series of the Verte- 
brates—of the brain-bearing Vertebrates at any rate. It is evident 
that beneath the neural axis, which arises in ‘ epiblast, there is 
a foundation, laid in ‘mesoblast,’ of the whole animal, from its snout 
to the end of its tail. This foundation, or rather root-stock, is double, | 
and each moiety lies right and left of a truly azygous structure, the 
notochord—a structure which, according to some, arises in the meso- 
blast also, but which, according to the latest and best observations 
(namely, those of Mr. Balfour), arises, in the Selachians at least, in 
the lowest layer, the ‘ hypoblast.’ Whether the notochord is meso- 
blastic or hypoblastic, at present is not of vital moment to the 
morphology of a vertebrated animal: the important points are that 
the notochord is universal, and that it always passes some distance 
into the skull, There are several important modifications in the 
region of the head, as compared with the body generally, that make 
the problem of cranial morphology an extremely difficult one. To 
mention some, there are: (1) the swelling of the neural axis into 
three vesicles ; (2) the flexure of the head upon itself; (8) the de- 
velopment of three pairs of sense-capsules, that press upon its sides 
and mingle with its structures; (4) the union of a palatal diver- 
ticulum with the brain to form the pituitary body, thus arresting 
the median notochord ; and (5) the dying out of the pleuro-peritoneal 
space in the region of the throat. Thus the modifying causes are 
manifold in the head of a vertebrated animal,—some of them showing 
their effects very early in the life of the embryo; whilst others, that 
relate to the specializations of the parts of the cranium and of the 
parts of the face, the parts that encircle the mouth and sense- 
capsules and that form the basket-work of the branchial apparatus— 
these appear later.” 
The Embryonic Membranes in Plants.—Professor Famintzin has 
published a valuable paper on this subject in the ‘ Botanische 
Zeitung,’ which is thus abstracted in the ‘ Academy’ (December 30) :— 
‘“«'The main purpose of the paper is to furnish the proofs of his theory 
of the development of the initial layers, or embryonic membranes, in 
plants. Hanstem had previously pointed out the existence of three 
distinct layers in the developing embryo of Capsella bursa-pastoris, 
and several Composite. The further development of these ‘ three 
systems of tissues,’ Famintzin asserts, has proved to be perfectly 
identical with the formation of the embryonic membranes in animals. 
While the embryo is still quite small, and before there is any trace 
of the cotyledons, the plerome forms an axile cylindrical cord, 
sheathed in two layers of cells, the periblem and the dermatogen. 
Soon divisions appear in the dermatogen at the lower end of the 
* «Proceedings of the Royal Society,’ vol. xxv. No, 175. 
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