and ammonia into the portal vein, and the injection of phosphoric acid into the circulation, and by the frequent, if not invariable, association of glucosuria with boils and carbuncles, and, according to Schiff,

with gangrene.

Thirdly, lesions of the nervous system, causing the removal of the influence which it exercises, during life under natural conditions, of holding in check the strong chemical tendency of amyloid substance to undergo transformation into sugar; the operations of this cause being well illustrated by the rapid production of sugar in the liver after death, and by the saccharine condition of the urine induced by maintaining the circulation by artificial respiration for an hour or so after the destruction of life by pithing, by woorali poison, and by strychnia ; also by lesions of certain portions of the nervous system, especially of the medulla oblongata (as in Bernard's experiments), and of different parts of the sympathetic (as in Dr. Pavy's own experiments). The glucosuria produced by these lesions, however, is only of a temporary nature, and, in the opinion of Dr. Pavy, due to an influence produced on the circulation of the liver.

Against Dr. Pavy's theory, that diabetes, in its most serious form, is caused by the downward meta

morphosis of amyloid substance, or glycogen, into sugar by the different classes of unnatural conditions just stated, important objections may reasonably be urged.

In the first place, a temporary saccharine condition of the urine, produced by experiments on animals, and by certain abnormal conditions in the human subject, cannot be regarded as identical with diabetes in which there is a permanent glucosuria intimately connected with a persistent mal-assimilation of food-a connection which can be as clearly traced in the more severe cases, where there is malassimilation of albumen, as in the milder form in which starch and sugar only undergo a diabetic metamorphosis.

Secondly it has not been demonstrated by well authenticated observations, so far as I am aware, that amyloid substance exists in the liver in confirmed cases of diabetes.' It certainly by no means follows that because it is a normal constituent of the liver, in healthy subjects, it must also be secreted by that organ in diabetics.

It has often occurred to me that diabetes may possibly depend on perverted functional action of

1 The observations of Grohe on this subject require confirmation (Greifswald's Medicinische Breiträge, B. iii, ii, i.)

the liver-cells whereby they morbidly secrete diabetic sugar instead of glycogen, their normal secretion. This is a much simpler explanation of the nature of the disease, and it is, moreover, not at variance with our knowledge of the varied secreting power of gland-cells, or glandular epithelium, of which the liver-cells are a modification. For example, the secreting gland-cells of the mammary glands, during the period of lactation, secrete lactin, or milk sugar, which closely resembles diabetic sugar; and this too in animals subsisting on food containing not a trace of starch or sugar. Thus we know that milk sugar is found in the milk of the carnivoræ, and of dogs fed exclusively for months on an animal diet. Judging from analogy, then, may not grape sugar be secreted by the glandular cells of the liver, as an abnormal secretion, in diabetes? We could thus account for the appearance of functional activity which this organ frequently, if not generally, presents after death from the disease. This opinion of the probable nature of diabetes, it must be admitted, is purely conjectural, but in this respect it is not more objectionable than the hypotheses already advanced on the subject.

With regard to the two distinct types or forms of diabetes described by Dr. Pavy, it is necessary to

observe that clinical observation goes far to establish that they are merely different stages of one and the same morbid process or affection. The form of the disease in which there is a mal-assimilation of the starchy and saccharine principles of the food only, represents its initial or primary stage, often extending over a lengthened period. A time, however, arrives in the history of cases belonging to this category when sugar continues to be excreted by the urine notwithstanding the complete exclusion of starch and sugar from the food, or, in other words, when a portion of the albuminous alimentary compounds also undergo saccharine transformation.

The class of cases constituting the other form of the disease, in which, Dr. Pavy justly observes, there is something besides a loss of assimilative power over starch and sugar, comprises those instances in which the malady has not been detected, or come under observation, until the development of the second stage. In support of this opinion it may be stated that it has not been established by clinical observation that in the initial period of diabetes sugar is ever formed from the albumen of the food. But it is necessary to prove that such a transformation really does take place before the existence of two distinct forms of the disease can be admitted.

That the two supposed types are but different stages of the same malady was first suggested by Traube, and is supported by the opinion of Dr. Parkes, who observes that, in some cases-perhaps in all(Traube's and my own, for example) the formation of sugar from albuminous food is a more advanced stage of the condition in which sugar is formed only from starchy compounds.'1

Such, then, are the most plausible theories which have been advanced, attributing diabetes to some morbid cause or process seated either in the alimentary canal or in the liver, and producing a malassimilation and misappropriation of the food taken for the nourishment of the body.

As yet we certainly do not possess any certain knowledge as to the origin of the disease, or as to the location and nature of the primary or essential morbid action producing the saccharine condition of the blood, which, in its turn, developes most of the important phenomena of the disease. We know that there is a primary and fundamental condition which continues throughout the whole course of disease: namely, an arrest of the normal metamorphic changes of starch and sugar. To account for this, Von Dursch conjectured that some substance

1 On the Urine, p. 348.