In relation to this subject it is interesting to bear in mind that alkaloids to which the name of ptomaines has been given (p. 99), are formed in dead bodies during the process of decomposition, and that when a solution of peptone is treated with potash and ether it yields a body which appears to be a volatile alkaloid. If putrid peptone is treated in the same way, a solid non-volatile alkaloid is obtained.2

Ptomaines are not only formed in dead bodies, they are also formed in the intestine by the decomposition of parts of its contents. They have been found in large quantities by Bouchard both in the stools of persons suffering from diarrhoea or typhoid fever, and in normal faeces. They appear to be absorbed from the intestine into the blood and excreted by the urine. They have been found by Bouchard in the urine both in health and disease, and Bocci has shown that the human urine has a paralysing action on frogs like that of curare, or of the ptomaines which Mosso and Guareschi have obtained from putrefied fibrin or brain.

Some time ago I pointed out3 the resemblance between the languor and weakness which occur in many cases of indigestion and the symptoms of poisoning by curare, and drew attention to the probability that the languor was due to the effect of poisonous substances absorbed from the intestine. These I considered to be probably peptones, but it is possible that they may be ptomaines. But whether the poisonous substances be peptones or ptomaines, the function of the liver is equally important in preventing them from reaching the general circulation.

1 Lautenbach, Philadelphia Medical Times, May 26, 1877.

2 Tanret, Comptes Rendus, xcii. 1163.

3 Lauder Brunton, 'Indigestion as a Cause of Nervous Depression,' Practitioner, vol. xxv. October and November 1880.

Bearing in mind, then, the office of the liver as a porter to prevent the passage of injurious substances from the intestinal canal into the blood, and the great effect that any alteration in the circulation through it may produce upon the circulation, and consequently on the functions of all the intestinal organs, we shall much more readily understand the importance of this gland, the largest in the body, than if we look upon it simply as an instrument for secreting the bile which plays a useful, but still subordinate part in the process of digestion.

We are still but imperfectly acquainted with its functions, but we may say that they are at least five: 1st, to form and store up glycogen, a material which will afterwards be used in evolving heat and muscular energy; it will thus, as it were, perform the office of a kind of coal-bunker to the body;

2ndly, to secrete bile for use in digestion;

3rdly, to excrete bile;

4thly, to destroy peptones which are poisonous when they are directly introduced into the general circulation, and to convert them into glycogen, etc.;

5thly, to destroy or store up and excrete other organic poisons which may have been formed in the alimentary canal during the process of digestion, or may have been introduced into it from without.

The glycogenic function of the liver is influenced by a number of drugs, especially phosphorus, and substances belonging to the same chemical group. Phosphorus, arsenic, and antimony, all destroy the glycogenic function, and at the same time tend to cause fatty degeneration of the organ. It is possible that these effects of the poisons are closely connected, but the exact connection between them has not yet been ascertained.

In consequence of the disappearance of glycogen from the liver which is caused by these drugs, puncture of the fourth ventricle will no longer cause glycosuria in animals which have been poisoned by them. Attempts have been made to utilise this fact in the treatment of diabetes, but as yet the results have not been very satisfactory.

Hepatic Stimulants. - The action of drugs on the secretion of the liver has been very carefully studied by some observers, especially by Rohrig, Rutherford, and Vignal. The mode of experimenting was to curarise a dog, ligature the common bileduct and insert a cannula into it. The bile was thus entirely prevented from reaching the intestine, and the whole of it flowed through the cannula into a vessel in which it was collected, so that the amount secreted in a given time was readily estimated. The drug was then administered, usually by injection into the duodenum, and the increase or diminution which this caused in the bile was noticed.

The ingestion of food greatly increases the secretion of bile, and in order to get rid of this disturbing factor, the experiments were all made on fasting animals.

A great number of drugs were experimented upon, some of which were found to stimulate the liver, and increase the quantity of bile without altering its quality, so that their action upon the liver would be nearly analogous to that of laxatives upon the intestine; others increased the quantity of bile, and rendered it more watery; others again had little effect upon the liver, but stimulated the intestinal secretion and movements.

The following are hepatic stimulants :Acid, dilute nitrohydro-chloric.1 Aloes.1

Rochelle salt.3 Sodium sulphate.2 Sodium phosphate.1 Potassium sulphate.2 Mercuric chloride.1 Sodium salicylate.1 Sodium benzoate.1

Ammonium benzoate.2 Baptisin.2 Euonymin.1 Hydrastin.2 Juglandin.2 Iridin.1 Leptandrin.2 Phytolaccin.1

Podophyllin.1 Sanguinarin.1 Colchicin.1 Colocynth.1 Jalap.2 Rhubarb.2 Ipecacuanha.1 Physostigma 3 (extract).

Those drugs which stimulate the intestine much, as a rule increase only slightly the secretion of bile by the liver, and podophyllin, which in certain doses acts as a powerful hepatic stimulant, ceases to have this effect when it produces marked purgation. These effects occur independently of the action of the drugs on the re-absorption and re-secretion of bile, inasmuch as in the experiments quoted the whole of the bile was collected directly from the liver and not allowed to pass at all into the intestine. A large number of substances belonging to the aromatic series act powerfully on the liver. Some of them, like salicylate of sodium, greatly increase the watery constituents of the bile, so that it is not only more abundant, but much more dilute than normal. Others of them, e.g. toluylendiamine, increase the solids to such an extent that the bile becomes so viscid that it cannot flow through the bile-ducts, and being absorbed gives rise to jaundice. A number of bitters belong to the aromatic series (p. 364).

1 The most powerful stimulants in the preceding list are indicated by (1), the less powerful by (2) and (3).

It seems not improbable that by further observations many aromatic compounds may be arranged in a regular series, according to their action on the solid and liquid constituents of the bile.