388 
POPULAE SCIENCE EEVTEW. 
tines. The chief plexiform layer of nervous tissue in the intestinal wall is 
always situated between the circular and longitudinal layers of muscle, and 
the fibres of which it is composed have generally a circular disposition. They 
are found throughout the whole of the intestine, and contain numerous 
ganglia. In the higher animals the development is considerably greater than 
in the lower ; and the larger the animal, the coarser are the fibres, and the 
wider are the meshes of the network. The nervous plexus of the intestine 
is intimately connected, on the one hand, with the great centres of the nervous 
system, through the mesenteric nerves ; and on the other hand with 
the pneumogastric nerves through its communication with the gastric 
nervous plexus. It is also connected with the nervous layer, lying 
beneath the mucous layer of the intestine. The connection with the mesen- 
teric nerves is accomplished through a plexus which lies beneath the serous 
layer of the intestine. The histological constituents of the plexus mesen- 
tericus are fine primitive nerve-fibres, ganglion-cells, and connective tissue. 
The fibres are grouped in bundles of from two to four, or four to eight, sur- 
rounded by a delicate nucleated sheath. — Vide Medico-Chirurgical Review, 
J anuary. 
Cause and Cure of Cataract . — Sir David Brewster, to whom we owe so 
much for his researches upon the structure of the crystalline lens, lately read 
a paper before the Eoyal Society of Edinburgh upon the above subjects. 
Having himself, about forty years ago, experienced a slight attack of cataract, 
he was led to make a number of investigations into the structure of the crystal- 
line lenses of various animals. From these researches he concluded that the 
cause of the disease was simply an insufficient supply of the proper fluid of 
the lens (liquor Morgagni), and hence the separation of the various lammm 
which compose this body. The cure was effected in eight months, by copious 
and continued doses of “ compound saline powder.” Sir David im*agined 
that the supply of fluid to the crystalline lens might be derived from the 
vitreous humour, and that the cataract might result from too large a per- 
centage of albumen in that secretion. The cure might then be effected either 
by injecting distilled water into the aqueous humour, or by tapping the 
aqueous chamber, in the hope that the newly-formed secretion would contain 
less albumen than the pre-existing one. The cure of soft cataract, on the other • 
hand, might be effected by the introduction of additional albumen into the 
aqueous chamber. Sir David has called attention to these views, because, 
though originally put forward many years ago, they have since been fully 
confirmed by ophthalmic surgeons. 
The Function of the Spleen, according to M. Ester’s newly-announced 
views, is connected with the amount of oxygen present in the gastric blood. 
From several experiments, he finds that during active digestion, the blood of 
the splenic vein contains only half as much oxygen as when the stomach has 
been for some time empty. 
METALLUKGY, MINERALOGY, AND MINING. 
Coal-mining Machinery . — An improved apparatus for getting coal has 
been described by Mr. W. W. Burdon. He proposes to employ a hammer 
or piston, driven by steam or air, to work upon a pick by blows on the head. 
