far to disprove the validity of Bernard's glycogenic function altogether. Dr. Pavy, after repeating Bernard's experiments, satisfied himself of the accuracy of the facts advanced by the latter; but he, at the same time, raised the question whether the conclusions drawn from them are not unwarrantable in consequence of being subject to a source of fallacy which had escaped detection. Dr. Pavy performed a series of experiments for the purpose of deciding whether the results obtained by Bernard's investigations on animals after death actually represent what is in operation, or really exists, during life; in other words, whether the post-mortem conditions described by him represent the ante-mortem or physiological state.

Dr. Pavy found as the result of his experiments, of which he has given full details in his work already referred to, that when the liver is removed instantly after death and quickly subjected to the action of caustic potash, or to a freezing temperature, or to boiling water, so as to prevent the occurrence of post-mortem changes, no sugar whatever can be detected in the liver, but that amyloid substance (glycogen) is readily obtained. He also discovered that during life, under normal conditions, there is scarcely any appreciable difference in the quantity

of sugar found in the blood drawn from different portions of the vascular system, whether from the systemic arteries or veins, or from the vena portæ, or, by means of a catheter, even from the right auricle; the actual amount of sugar obtained from all these different points of the circulating current being exceedingly minute, namely: from 47 to 73.1000ths of a grain per cent.

From these observations Dr. Pavy drew the following important conclusions:-

Firstly, that during life, as a natural condition, no sugar is found in the liver, or secreted by that

organ.

Secondly, that normally during life scarcely any glycogen is transformed into sugar and taken up by the blood in its passage through the liver, in consequence of its colloidal character rendering it incapable of dialising through animal membranes.

Thirdly, that the sugar found so plentifully after death in the liver, and in the blood of that portion of the circulation intervening between it and the lungs (as revealed by the accurate experiments of Bernard), is produced by post-mortem changes and the development of a ferment in the liver itself, and that the evidence on which it was believed that the liver exercises a sugar-forming function was

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based on conditions occurring after death, and differing essentially from those existing during life. Consequently, to use Dr. Pavy's own words, there is not that flow of sugar into the circulation from the liver for the purpose of destruction in the lungs, which the former mode of experimenting led physiologists to believe existed.'

It may be here mentioned that numerous unsuccessful efforts have been made to discover the source of the ferment which Bernard supposed to be required to transform the glycogen in the liver into sugar. Thus Schiff extirpated the thymus, the thyroid, the salivary, and pancreatic glands, the spleen, and the supra-renal capsules in succession, without obtaining any information on the subject. According to Henson, the ferment is precipitated with the glycogen by the addition of alcohol to the cold aqueous infusion of the liver, that it is rendered inoperative by boiling, as was previously observed by Bernard, and that it is contained in arterial blood, and in the blood of the vena portæ, inasmuch as this blood has the property of converting a solution of glycogen into sugar. The existence of any special ferment, however, appears to be altogether hypothetical; although Dr. Pavy has pointed out that when glycogen is introduced into blood it is quickly converted into sugar.

Dr. Pavy believes that there are two distinct types or forms of diabetes.

In one form (the milder) he is of opinion that the only error existing is a want of proper assimilative power over sugar; in some of the cases of this class there is a total loss of assimilative power, so that if any starch or sugar is ingested, sugar will appear in the urine; in others, again, there are various degrees of diminution, so that the urine becomes saccharine only when more than a certain quanty of starch or sugar has been consumed; cases of this class, he considers, are not uncommon among elderly people.

In the other form of the disease, including the majority of cases the bulk, indeed, occurring in young subjects and in those below the middle period of life—there must exist, Dr. Pavy thinks, something additional to the want of assimilative power over sugar, inasmuch as the urine continues to be saccharine even when starch and sugar are carefully excluded from the food. To account for this occurrence, he considers we must look to the amyloid substance (glycogen) existing largely in the liver, as reasonably constituting the source of the sugar in the urine; this substance being exceedingly prone to undergo a downward metamorphosis into

sugar. Normally,' says Dr. Pavy, this metamorphosis is prevented from taking place to more than a barely appreciable extent; but under various unnatural circumstances it is more or less freely allowed to occur, and as the result, sugar appears to a corresponding extent in the general circulation, and from thence finds its way into the urine;' diabetes being thus produced.

The unnatural conditions which, according to Dr. Pavy, lead to the transformation of glycogen into sugar, are capable of being grouped into three distinct classes.

Firstly, a congested condition of the blood-vessels of the liver, giving rise to an unnatural relation between its cell contents and the blood-vessels, causing the escape of amyloid substance into the blood current, and its immediate conversion into sugar. The causes producing this vascular congestion being obstruction of the process of respiration, however produced, as for example by whooping cough, pneumonia, coma, and the inhalation of chloroform and other vapours.

Secondly, a change in the quality of the blood passing through the liver, as shown by the production of a saccharine state of the urine experimentally by tying the portal vein, by the injection of ether