been made, and for which I am indebted to Charles' 'Physiological Chemistry.' This table is chiefly interesting as showing the great increase of fat in fatty livers, and of gelatin due to the overgrowth of connective tissue in a cirrhotic liver. In a liver that had undergone acute atrophy Röhmann found albumose and peptone, sarco-lactic acid and a mixture of amido-acids, alanine, leucine, and tyrosine being the most abundant. The latter were absent from the urine, which contained, however, excess of aromatic oxy-acids.

THE SPLEEN

'The spleen is invested with a fibrous and muscular capsule, and this again has a covering derived from the serous membrane. The capsule sends fibrous bands or trabecula into the organ, and these join with similar trabecula which pass in at the hilus with the blood-vessels. In the interstices of the framework so formed lies a pulpy substance containing blood, and therefore of a red colour, within which are seen small whitish specks, the Malpighian corpuscles. These are composed of lymphoid tissue which is gathered into masses which envelop the smaller arteries, while the pulp which everywhere surrounds them is composed of a close network of flattened and branched cells like connective-tissue corpuscles. Coursing through the pulp and communicating with its interstices are capillaries connected with the terminations of the arteries: in other parts venous channels arise from the pulp and bring the blood which has passed into its interstices from the arterial capillaries towards the larger veins of the organ which run in the trabeculæ and are by them conducted to the hilus.'

'The cellular elements of the pulp are of three kinds, viz. peculiar large amoeboid cells called splenic cells, lymph-corpuscles, and the branched cells which form the sponge-work. The first named are,

1 P. 355.

2 Berlin. klin. Woch. 1888, Nos. 43 and 44.

frequently found to contain coloured blood-corpuscles in their interior in various stages of transformation into pigment.'

The foregoing brief account of the histology of the spleen taken verbatim from Schäfer's 'Essentials'' shows us the number of microscopic elements with which we have to deal, and thus the large number of chemical substances obtainable from the spleen is fully accounted for.

Chemical composition of the spleen.- Oidtmann' states that the percentage of water in the adult human spleen varies from 694 to 77·5; the solids from 31.6 to 22.5, of which from 301 to 21.6 consist of organic, and from 1.1 to 0.9 of inorganic matters.

6

The organic constituents that have been described are proteids and hæmoglobin; xanthine,3 hypoxanthine,3 uric acid,' glycogen, inosite, scyllite, cerebrin, cholesterin, lecithin, and jecorin in small quantities. Gelatin and mucin are also present and are derived from the supporting connective tissue.

Various fatty acids (formic, acetic, butyric) described by Scherer 10 are no doubt derived during the process of distillation from the proteids and hæmoglobin (Hoppe-Seyler).

Leucine and tyrosine, which are often found, are the result of putrefactive changes; they are absent in the fresh organ (HoppeSeyler).

Lactic and succinic acids were found by Gorup-Besanez. The variety of lactic acid present is sarco-lactic acid (Hirschler "). This appears to be especially formed after death, giving to the spleen an acid reaction. During life the spleen is alkaline.

The inorganic constituents. These are very much like those found in the liver. Oidtmann gives the following analysis; the numbers are percentages of the ash :-Soda, 35-45; potash, 9-17; lime, 7; phosphoric acid, 18-30; oxide of iron, 7-16; chlorine, 0·5-13; sulphuric acid, 1.5-2.5; silica, 0·2-0·7; manganese, copper, and lead in traces.

One of the most interesting of these constituents is iron. In the splenic pulp of old horses H. Nasse 12 found that nearly 5 per cent. of the dry residue consisted of iron. The iron is present in organic combinations, and mostly as hæmoglobin. Hoppe-Seyler regards other organic

3 Scherer, Ann. Chem. Pharm. evii. 314; Städeler, Ibid. cxvi. 102; Neubauer, Zeit. anal. Chem. vi. 33; Gorup-Besanez, Ann. Chem. Pharm. xeviii. 1; Cloëtta, Ibid, xcix. 4 Scherer, Cloetta, Gorup-Besanez.

289.

5 Hoppe-Seyler, Med. Chem. Unters. iv. 495; Abeles, Centralbl. med. Wiss. 1876, No. 5. 6 Cloetta, Scherer.

7 Frerichs and Städeler, Mitth. Züricher naturf. Gesell. 1855.

8 Hoppe-Seyler.

9 Baldi, Du Bois Reymond's Arch. supp. 1887, p. 100.

10 Verhandl. Würzburger phys. med. Gesell. ii. 323.

11 Zeit. physiol. Chem. xi. 41. 12 Quoted by Hoppe-Seyler, Physiol. Chem. p. 720.

compounds containing iron which have been described as artificial or post-mortem decomposition products of hæmoglobin. Lapique states that the spleen of young animals contains less iron than that of adults, which is the opposite to what is the case in the liver.

Functions of the spleen. The lymphoid tissue is no doubt a place for the manufacture of white blood-corpuscles. With regard to the red corpuscles, some hold that they are destroyed, others that they are formed, and others again that both processes may occur in the spleen.

The splenic cells are also believed to liberate hæmoglobin from 'effete' corpuscles, which, passing to the liver, is there transformed into bile-pigment. This is erroneous, but the question will be considered again in connection with the bile. Schiff and Herzen supposed that the spleen also manufactures the pancreatic ferment. Mosler has shown that this is, however, probably not the case.

The spleen has been removed from healthy animals (Galen) and also from the human subject without any bad results following. In certain animals, e.g. the dog, the operation has been followed by hypertrophy of other hæmopoietic tissues (lymphatic glands and red marrow); but in certain other animals, e.g. the rabbit, this does not appear to be the case. In the disease known as splenic leucocythæmia, in which the spleen is hypertrophied, there is a great increase of the white corpuscles of the blood (see p. 302). In this disease Charcot's crystals (see p. 303) are also found in the splenic pulp.

In progressive pernicious anæmia the destruction of blood in the liver and also in the spleen is much increased, and so an increased quantity of iron is found in those organs (see pp. 301, 552).

The administration of toluylenediamine produces similar results to those observed in pernicious anæmia (Engel and Kiener,3 Hunter).

In attacks of ague the spleen becomes enlarged, and this is apparently connected with increase of uric acid in the urine. After many attacks. the spleen becomes permanently enlarged and hard from the overgrowth of connective tissue.

LYMPHATIC GLANDS

These structures are composed of lymphoid tissue with an investing capsule and trabecule of fibrous tissue.

The connective-tissue structures yield the same chemical materials as this tissue does in general, especially gelatin and mucin.

The

1 Virchow, Hirsch, Med. Jahresb. 1870, i. 100 (original paper in Italian). See also

A. Herzen, Pflüger's Archiv, xxx. 295 and 308.

* Tizzoni, Internat. Monatsschrift für Anat. und Physiol. ix. 143.

3 Compt. rend. cv.7465.

lymph-cells are simply white blood-corpuscles, the chemistry of which has been already described (p. 258).

In a lymphatic gland about two-thirds are water, the remainder solids.

The gland is alkaline during life, and turns acid after death. The acid present is sarco-lactic acid (Hirschler1). In the overgrowth of lymphoid tissue that occurs in scrofula and tubercle, there is a great tendency for the new tissue to undergo degenerative changes, caseation and softening, leading to the formation of cavities and abscesses. In the condition of hypertrophy known as lymphadenoma, this tendency is absent.

THYMUS

This body is also lymphoid tissue, and contains the same substances as the lymphatic glands.

Its cells, like those of the lymphatic glands, have been already described in connection with the blood (p. 258).

The so-called 'concentric corpuscles,' which are peculiar to the thymus, do not seem to yield any special chemical substance.

Towards puberty the thymus undergoes fatty degeneration, and is a mere mass of adipose tissue in the adult.

The presence of extractives like xanthine, hypoxanthine, &c. has been noted by Scherer, Gorup-Besanez, Frerichs, Städeler, &c. whose writings have already been referred to. In fact these substances appear to be constantly present in all structures rich in cellular elements.

Schindler 2 has estimated these nitrogenous bases quantitatively in the thymus of the calf, with the following results :

The high percentage of adenine (a base derived from nuclein; see

p. 203) is especially noteworthy.

Like all the other organs also that we have examined, the reaction, alkaline during life, becomes rapidly acid after death. This acid is sarco-lactic acid (Moscatelli 3).

1 Zeit. physiol. Chem. xi. 41.

2 Schindler, Zeit. physiol. Chem. xiii. 438.

3 Zeit. physiol. Chem. xii. 416.

THYROID

This is also a cellular organ, and proteids (including globulin and a mucin-like substance) and various extractives have been found in it (fatty acids, xanthine, hypoxanthine, &c. by Gorup-Besanez, Scherer, Frerichs, and Städeler). Alkaline in life, it becomes acid after death: this is due to sarco-lactic acid (Moscatelli).

In the adult, the mucin-like material of the alveoli is converted into colloid substance, the properties of which were described in connection with ovarian tumours (p. 353).

Cysts of the thyroid. In the simple large cysts of the thyroid the fluid is richly albuminous, containing 7 to 8 per cent. of proteids consisting of both serum-globulin and serum-albumin. They may, however, be sometimes filled with colloid material, and very often numerous crystals of cholesterin are seen in the liquid.

Altered blood-corpuscles and altered blood-pigment, such as methæmoglobin or crystals of hæmatoidin, are often found (HoppeSeyler 1).

Myxedema. The most constant pathological condition in this disease is atrophy of the thyroid gland, its proper substance being replaced by fibrous tissue. The condition of the blood and connective tissues in this disease has been already fully described (pp. 304 and 501). Horsley believes that some of the degenerative changes of old age may also be attributed to wasting of the thyroid. It is, however, possible that in this case the wasting of the thyroid is not the cause of senile decay, but only a part of the general wasting that occurs in

old age.

SUPRARENAL BODY

The function of this organ is unknown, like that of so many of the other so-called ductless glands. It is composed again largely of cells, and in addition to the usual extractives present others have been found by different observers; thus Cloëz and Vulpian 2 found hippuric and taurocholic acids, Seligsohn 3 found benzoic acid and taurine; Holm also found taurine. It is possible that these substances may be absorbed from the neighbouring gall-bladder and kidney. Külz3 found inosite to be present.

The medulla of the suprarenal is rich in nervous elements, and contains a substance which is soluble in water, and which furnishes

1 Physiol. Chem. p. 722.

2 Compt. rend. ii. 1857, p. 10; Gaz. méd. de Paris, 1858, No. 24. 3 Diss. Berlin, 1858.

4 Journ. prakt. Chem. c. 150...

5 Sitz. Marburger Ges. zu Beford. d. ges. Naturwiss, 1876, No. 4..