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No. 3.-Podura scale (test), view of markings? beads in the notes of admiration! and general roughness of the scale.

No. 4.-A, Podura scale (test), view of faint markings? beads on the ribs.

No. 5.-A, A, Podura scale (test), similar to No. 4, but rather larger.

No. 6.-B, B, Podura scale (test), somewhat similar view, with rather larger markings shown on the ribs.

No. 7.-I, i, Degeeria domestica (speckled), view of the markings on the ribs ? beads and slight waviness of the scale.

No. 8.-J, j, Degeeria domestica (speckled), view of the markings on the ribs? beads, second set showing faintly.

No. 9.-K, Degeeria domestica (speckled), view of the markings on the ribs ? beads, rather deeper focus than No. 8.

No. 10.-L, Degeeria domestica (speckled), view of the markings on the ribs? beads, with slight waviness; also in parts the two sets of markings.

No. 11.-M, Degeeria domestica (speckled), view focussed for the best general view of the scale and markings, which Dr. Pigott regards as "the best approximation view of the set."

No. 12.-N, Degeeria domestica (speckled), view focussed to show two sets of markings? beads————

No. 13.-0, Degeeria domestica (speckled), view to show the markings? beads, in the interspaces or the notes of admiration !!

No. 14.-P, Degeeria domestica (speckled), view to show the two sets of markings? beads, as the ribs unite or pass each other obliquely.

The photographs of L. curvicollis are from the same scale on a slide given me by my friend the late R. Beck; those of Degeeria are also from one scale on a slide kindly presented to me by Mr. McIntire. The magnification ranges from 920 to about 1920 in the former, and about 1300 in the latter.

I must trust to the interest in the photographs as compensatory to the above details.

IV.-Description of a simple Air-Sieve.

By METCALFE JOHNSON, M.R.C.S.E., Lancaster.

IN Art. VII., M. M. J., August, 1869, it is stated that "By means of an air-sieve I have collected distilled water trickled over a glass plate into a trough, and found varying quantities of Monas Lens, besides other air-contents."

It is desired in the present remarks to describe this "air-sieve," in the hope that others of your readers may be induced either to employ it and test its accuracy, or to point out the sources of fallacy, and thus bring about a more perfected experiment.

The apparatus I have made use of consists of a small deal box about 12 inches square, having an opening to the front with sloping sides, so as to direct the current of air directly upon the surface of a glass plate, which slopes (at an angle of about 22°) from a vessel containing distilled water, at the upper part of the box, to a trough placed at its base. The water is caused to trickle slowly over the glass plate by means of a cloth siphon from the upper vessel. In its course it comes in contact with the air, which is conveyed in a current through an open window into a room whose temperature is greater than that of the outer air, thus causing a traversing of the air of "out-o'-doors" to the inner chamber. The box contains a smaller opening to the chamber, through which the current can be detected. The water which trickles over the plate is then collected in the trough at the bottom, which, when examined microscopically, shows the presence of Monas Lens upon its surface, and when tested by solutions of potassic permanganate, by means of a volumetric analysis burette, shows varying proportions of organic matter present.

One noticeable fact is that the presence of monads is always, in these experiments, best discovered by examining the surface of the liquid. By the use of water, as in the apparatus described, the particles floating in the air are seized in a way which produces no injury, and the surface brought into contact with the air is larger than in Prof. Angus Smith and Dancer's experiments.

V.-The Microscopic Structure of the Human Liver.
By Dr. H. D. SCHMIDT, of New Orleans.*

PLATE LVIII.

THE human liver, like that of all vertebrated animals, is composed of three principal parts. The first comprising the blood-vessels, ducts and lymphatics, which convey the fluids either to or from the organ; the second, the special instruments of secretion, viz. the cells with free nuclei and granules; the third, the nerves which stimulate and regulate the functions of the organ.

The blood-vessels conveying the blood, both venous and arterial, to the liver, are the portal vein and hepatic artery, which enter it at its inferior surface. Those conveying the blood from it are the hepatic veins, which, taking their exit posteriorly, join the ascending vena cava. The hepatic duct-carrying off the secretion of the

* A reprint of this valuable paper which was originally published in the 'New Orleans Journal of Medicine' (October, 1869), reached us quite lately. As the views Dr. Schmidt enunciates differ materially from the opinions of Drs. Beale and Handfield Jones, who themselves represent opposite schools, we have thought them worth reproducing, at least in part, in these pages.—ED. M. M. J.

organ, the nerves and lymphatics always accompany the portal vein and hepatic artery.

The vessels and the duct, after having entered the liver, divide and subdivide until their ultimate branches have become small enough to pass into capillary networks.

The space between the branches of the vessels, &c., is occupied by the parenchyma of the liver, which consists of two capillary networks perfectly independent of each other the meshes of which are filled up by the hepatic cells, free nuclei, and granules. One of these networks originates in the ultimate branches of the portal vein and hepatic artery, and terminates in the smallest

EXPLANATION OF PLATE LVIII.

FIG. 1 represents the termination of the finest branches of the portal vein and hepatic artery in their capillary network, and the commencement of the finest branches of the hepatic duct in the network of "biliary tubules." On the left side the capillary network of the blood-vessels alone is represented; on the right, its relationship to the network of biliary tubules, from which the finest branches of the hepatic duct arise, can be seen. a, intra-lobular branch of the portal vein; b, intralobular branch of the hepatic artery,-both these vessels are seen to terminate in the same capillary network. c, intra-lobular branch of the hepatic duct,-its finest ramuscules are seen to arise in the network of biliary tubules. The latter, in order to distinguish them from the capillaries which carry the blood, have been shaded very dark. d, transversely oblique section of an intra-lobular hepatic vein, showing the manner in which it receives its capillaries; e, capillaries for the blood; f, biliary tubules, or capillaries for the bile. The above drawing is a composition taken from four different specimens of sections of human liver. Magnified 90 diam.

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2.-Plexus of lymphatics in the capsule on the surface of the human liver: a, large lymphatic vessels, showing their characteristic sinuses, dilatations, and valves; b, portions of the network of biliary tubules, in which the finest lymphatic vessels are seen to arise; they are imbedded in a small portion of parenchyma which was left adhering to the capsule. Magnified 30 diam.

3.-Small portion from the capsule of the "portal vessels," showing the anastomoses of the small branches of the portal vein and hepatic artery; also the "hepatic glands" and the plexus formed by their ducts. a, branch of hepatic artery; b, branch of portal vein; c, plexus of hepatic glands; d, capillary network of the blood-vessels surrounding a portion of the glands. Magnified 30 diam. 4.-Diagramatic drawing, illustrating the relationship of the capillary network of blood-vessels, and that of the biliary tubules to the hepatic cells. a, terminal branch of portal vein; b, finest branches of the hepatic duct, arising in the network of biliary tubules; c, hepatic cells. The latter are seen to fill up the meshes of the network. 5.-Lymphatics of the capsule on the surface of the liver of the sheep. There is a small portion of the parenchyma left in the preparation, holding a portion of the network of biliary tubules from which the lymphatics can be seen to arise. Magnified 30 diam.

6.—a, a hepatic cell, partially torn with the needles of the "microscopic dissector," in order to examine its contents; the latter are seen to be drawn out in the form of filaments; b represents the same cell completely torn. Magnified 180 diam.

7.-A hepatic cell torn by a needle with a broken point. Magnified 180 diam.

The Monthly Microscopical Journal, Aug 11870.
Fig. 2.

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