PRODUCTS, ADVENTITIOUS. 



99 



having convex edges converging to a point at 

 either end, as before referred to. 



In the peculiar softening of the vitreous 

 humour called sparkling synchisis, the spark- 

 ling appearance at the bottom of the eye is 

 said (Bouisson) to depend on the presence of 

 molecules of cholesterin.* 



The development of masses of chole- 

 steatoma takes place, independently of blood- 

 vessels in its substance, by successive genera- 

 tions of layers of cells, each layer being 

 removed from the seat of its formation by 

 that following, precisely after the model of 

 epithelium. The cells being, as far as ob- 

 servation has gone, unprovided with nuclei, 

 and containing no sub-cells in their interior, 

 cannot be considered capable of producing 

 new cells ; the seat of true production there- 

 fore, as long as the mass continues to enlarge, 

 remains unchanged to the last. 



III. SUGAR. In a peculiar state of the 

 system, the essential nature of which is as yet 

 enveloped in obscurity, starch-sugar (identical 

 in all properties with glucose f) accumulates 

 in sufficient quantity in the blood to be easily 

 detected in that fluid by chemical analysis. 

 The same substance impregnates the secre- 

 tions and excretions, the urine, the faeces, 

 the perspiration J, the expectoration , and 

 (as is inferrible from certain experiments |j) 

 the gastric juice. 



In this disease (known as saccharine dia- 

 betes) the condition of the urine has always 

 clinically attracted the chief attention. Not 

 only is the sugar most easily discoverable in the 

 urine, but this fluid is otherwise strikingly 

 altered in qualities : its specific gravity ranges 

 from 1028 to 1055 H ; while its amount varies 

 from two or three to seventeen pounds in the 

 course of twenty-four hours. The connection 

 of albuminuria with diabetes is matter of dis- 

 pute. Cotunnius** observed long since that 

 albumen occasionally occurs in diabetic urine. 

 Schonlein states, that the presence of sugar is 

 preceded by that of albumen, the latter dis- 

 appearing, while, with the advance of the 

 disease, the former increases in quantity. 

 Thenard and Dupuytren, observing coagu- 

 lability of the urine occur in cases, where the 

 fluid had been excessively abundant and sac- 

 charine, regard albuminuria as of favourable 

 augury. M. Rayer-j-j- has frequently known 

 the change (as might be expected) announce 

 coming dropsy. Fat sometimes exists in suffi- 

 cient quantity in diabetic urine to render it 

 milky-looking. JJ The once popular idea 



* Banking's Retrospect, vol. vi. p. 286. 



f Thenard, Rayer, and Bouchardat formerly 

 maintained that diabetic urine sometimes contains 

 an insipid sugar, independently of, or in addition to, 

 the sweet variety ; but later observations disprove 

 the existence of any such body as the insipid sugar. 



t Nasse, Rhein. Corr. Blatt. No. vi. 1842. 



Francis, Lond. Med. Gaz. Feb. 12. 1847. 



I Those of Mr. M'Gregor ; vide note, next col. 



\ The specific gravity is in exceedingly rare cases 

 not raised much above the healthy standard; Dr. 

 Prout once found it even below this (1015). 



** De Ischiade Nervosa, p. 31. 1770. 



ft Mai. des Reins, t. i. p. 151. 



it Rayer, in L'Experience, t. i. p. 664. 



that sugar takes the place of urea in the urine 

 has been set aside by Mr. M'Gregor's investi- 

 gations, which show that the dally discharge 

 of urea may throughout not only equal, but 

 exceed, the healthy average. Deficiency of 

 urea (which sometimes occurs) can only be 

 regarded as accidental. 



Various theories of the pathology of dia- 

 betes have been started. Those of the or- 

 ganic class (gastric, renal, &c.) have hitherto 

 proved inadequate : the most accurate investi- 

 gations have failed to establish any textural 

 alteration antecedent in development to 

 sugar-accumulation in the blood. Doctrines 

 of the chemical class are in one point of 

 view more entitled to consideration. Rollo 

 originated these by ascribing the disease to 

 mal-assimilation in the stomach to decom- 

 position of vegetable food into sugar through 

 the influence of morbid gastric juice. Mr. 

 M'Gregor's experiments proved the produc- 

 tion of sugar in the stomach from amyla- 

 ceous substances*, and thus gave the appear- 

 ance of demonstration to Rollo's theory. 

 Nor can more modern speculations be said 

 to have done much else than to have shaped 

 that theory to the principles of advancing 

 chemistry. Of these speculations it appears 

 well to notice two. 



In the first of these the argument runs as 

 follows : In the natural state of the digestive 

 process sugar is not evolved from starchy mat- 

 ters, the formation of that substance stopping 

 at what may be called the dextrin stage : and 

 further, the economy is doubly guarded against 

 the passage of sugar, used as food, into the 

 secretions : first, by a power on the part of the 

 stomach of transforming sugar ; and secondly, 

 by a similar power on the part of the blood. 

 Now in diabetes, it is assumed, both these 

 powers are lost : swallowed sugar is not con- 

 verted ; and amylaceous matters are carried 

 beyond the dextrin stage of transformation, 

 and changed into sugar. But this doctrine of 

 the chemistry of the disease appears to fall 

 before the facts, that if much sugar be taken in 

 a state of health, (as by persons indulging in 

 punch to any amount,) the urine is distinctly 

 found to contain sugar : nay, even under ordi- 

 nary circumstances, sugar has been detected 

 (Buchanan) in healthy blood soon after a meal. 



The second theory, to which we shall refer, 

 may be deduced from the following document, 

 kindly supplied to us at our request by our 

 colleague Professor Graham. 



" The principal conclusions to which I have 

 been led by a comparative examination of the 



* Feeding a diabetic patient upon beef, Mr. 

 M'Gregor found sugar in the contents of the stomach 

 vomited immediately after a meal, and concluded 

 (a notion accepted by Berzelius as the basis of his 

 own theory) that the protein-compounds had been 

 converted into sugar. The true explanation of the 

 fact seems to be, that in this disease the blood con- 

 tains so much more sugar than natural, that a cer- 

 tain share is thrown out with the gastric juice, and 

 is of course discoverable immediately among vomited 

 food. It is matter of doubt with the best chemists, 

 whether sugar can be evolved from the much more 

 closely allied substance, fat. 



H 2 



