^ PROaRESS OF MICROSCOPICAL SCIENCE. 
215 
of picric acid for a few days, by which the spirit is expelled and the 
parts are again slightly hardened. After a few days, wash in pure 
water and plunge the preparation into a weak solution of gum arable, 
which completely penetrates the tissues in a few days. Then remove 
and place in alcohol, which takes up the water, and the gum solidifies 
and yields a mass which resists uniformly the cutting blade — micro- 
tome, or razor — according to convenience. When the section is made, 
the gum dissolves out after soaking a little while in water, and the 
preparation can be floated in the fluid selected for preserving it. 
Cells are of course needed for preparations of larger parts and organs. 
Gymnospermous Seeds of the Coal-measures. — In Professor William- 
son's recent memoir before the Eoyal Society (May 18), the author 
directs attention among other matters to the curious seeds discovered 
in America, and published in Professor Newberry's ' Geological 
Survey of Ohio.' These, however, merely display external forms. 
Still more remarkable is the collection of such seeds found by 
M. Grand-Eury at St. Etienne in France. These exhibit their 
internal structure in a wonderful manner, as is shown by M. Brong- 
niart's brief memoir published in the 'Annales des Sciences 
Naturelles.' M. Brongniart called attention, in that memoir, to a 
remarkable organization of the micropylar extremity of many of these 
seeds, where a peculiar cavity existed, between the micropyle and the 
apex of the nucleus, into which the pollen-grains obtained entrance 
through the micropyle, and were thus brought into contact with the 
nucleus. In a more recent memoir on the fertilization of the ovules 
of some species of recent Cycads (Ceratozamise), M. Brongniart showed 
that a mammillar prolongation of the apex of the nucleus projected 
into the micropyle, which it filled ; but that during fertilization the 
cells of this prolongation became disorganized, and a cavity was 
produced into which the pollen-grains found their way, the apex of 
the nucleus below this cavity becoming covered over by true peri- 
spermic membrane. These structural peculiarities so far accord with 
what he observed in M. Grand-Eury's seeds, as to lead him to surmise 
that the latter had Cycadean rather than Coniferous afiinities. The 
author has found a number of remarkable seeds of a similar type to 
those from St. Etienne in the Oldham nodules, and he has been 
indebted to friends for a few others. The first of these is a very 
small, nearly spherical seed, which the author names Lagenostoma 
ovoides, about '16 of an inch in length and '1 in breadth. It has a 
solid testa, within which can be recognized two distinct membranes 
— an inner or " perispermic " one, which has enclosed the endosperm, 
and an outer or " nucular " one, which has been in close contact with 
the perispermic one throughout the greater part of the seed, but 
which splits up at its apex into two portions, the inner one of which 
forms a remarkable flask-shaped cavity, which the author designates 
the lagenostome. Its base has rested upon the apex of the perisperm, 
and its upper extremity has been continuous with the micropyle. 
Within this lagenostome is a little delicate parenchyma, which has 
shrunk up towards the centre of the cavity, leaving a surround ing 
space in which, in some examples, the author has found the objects 
