THE ANALYST. 79 DETERNINATION OF GLUCOSE I N BLOOD AND OTHER ORGARIC SUBSTANCES. DR. PATP, F.R.S., recently read a paper before the ltoyal Society on a modification of thc methods previously in use for the quantitatiw determination of glucose in animal substances. There is no doubt that where minute traces of glucose are in question, Dr. Pavy’s method introduces improvements which must greatly conduce to the delicacy of such process, and although it can scarcely be considered as practicable in cGrnmercial analyses because of the time involved, it must necessarily form a material advance in our methods of procedure mbere delicate invcstigatiotis are concerned.The process consists essentially in an adaptation of the old gravimetric process of determination by means of a solution of sulphate of copper and double tartrate of soda and potash, the liquor being, however, irt the first instance mixed with an excess of solution of sulphate of soda aiid boiled, so as to coagulate it.The liquid is then filtered, and the potassio tartrate of copper added to the filtrate. Thc reduced sub-oxide of copper is then separated by filtration from theliquid, dissolved in a few drops of nitric acid, with a small quantity of per-oxide of hydrogen added t o effect oxidation, and the amount of copper prcsent in the precipitate, instead of being estirnllted as in the old process by direct weighing of the sub-oxide involving the necessary errors due t o the presence of the filter ash and t o other circumstances, is determined by galvanic deposition of the copper upon the surface of a piece of platinum foil or wire, which is weighed before and after the galvanic action.The results are calculated out according t o the old formula, viz., that 1 part of copper equals ,5678 of glucose. The author of the paper rightly states, ‘‘ This application of the copper test solution yields a gravimetric process of analysis instead of a volumetric, and one which has no uncertainty belonging t o it.There is nothing for the mind to do, and no opportunity for error of judgment.” Dr. Pavy subsequently read a second paper on this subject before the Royal Society. It is the issue of the application of the above process. Dr. Yavy dealt with the question of the quantity of sugar jn the system under the following conditions :- 1.The amount which exists in blood in its normal condition. 2. The comparative state of arterial and venous blood. 3. The spontaneous change which takes place in blood after its removal from the The author pointed out; that the very rapid changes mhich take place in blood under altered conditions of tho system render it essentially uecessary that the greatest system.80 THE ANALYST.precaution should be observed in order to obtain blood in its natural condition. I f taken during life the animal should be in a perfectly tranquil state. If after, it should be procured as instantaneously as possible after the death of the animal, so that no opportunity could be afforded for the blood to be affected by the post mortem production of sugar in the liver.The experiments now under notice were made on dogs, sheep, and bullocks’ blood, and a series of six, in one case seven, examinations of each kind instituted, and two analyses made for every sample taken. I n quoting Dr. Pavy’s figures we are giving the mean of the two separate analyses. It is necessary, however, to state that the extremes of each show but trifling variations, and these are rarely so great as to affect more than the second figure in ilecimals.The mean results of seven examinations of dogs’ blood showed the amount of sugar which it contained in parts per 1,000, to be as follows :-0.751, 0.786, 0.700, 0.766, 0.7S6, 0.921, 0.803 respectively. The blood of sheep yielded 0.470, 0.490, 0.517, 0.559, 0.569, 0.526, respectively, or an average of 0.521 parts of sugar per 1,000.The bullock’s blood gave 0.703, 0.525, 0.492, 0.456, 6.499, 0.588, or an average of 0.543. I n each of these experiments every care was taken to secure the blood in such a manner that it was a reliable representation of its ordinary condition during life, Unless such prccautions are taken the results obtained will be, in a physiological point of view, worthless and misleading.This fact was strikingly illustrated by a comparison of results which Dr. Pary obtained from four bullocks killed in the ordinary way, viz., by felling the animal with a poleaxe, and breaking up the spinal cord by means of a cane. I n the first two of these observations the opening into the blood vessels was made as speedily as possible after the animal had been felled.I n the next two Dr. P a v had rea80n to believe that this necessary condition had not been complied with, and that some little time was allowed t o elapse between the felling of the bullock and the opening of the vessels. The effect of this delay in the p o d mortem production of sugar is shown by the following results :- Blood of the first two bullocks (mean of two analyses) yielded 0.596, 0.688, parts of sugar per 1,000, respectively. I n the second two a mean of 1.053 and 1.094 parts of sugar per 1,000 were given.The conclusions to be drawn from these various experiments are, that the amount of sugar contained in the biood of sheep and bullocks is about per 1,000 or 1 in 2,000, and in a dog about Taking the results of the whole serics of observations they shorn a remarkable uniformity and harmony in the amount of sugar contained in the blood of the respective animals.This gives an average of 0.787 on the whole series. per 1,000, or 14 per 2,000. COiWAHATIVE STATE OF VEhTOCS ARB ARTERIAL BLOOD. The anthor next considered the comparative states of the arterial and venous blood. This part of the subject is olie which possesses the greatest importacce from a phy- siological point of view.One of thc effects of antvsthetics on animals is to occasion an abnormal amount of sugar in the blood, in order to attain accuracy, therefore it ie indispensable that blood should be takcn at c? timc when the animal is not under such influence,THE ANALYST. 81 In the first observation made on the blood of a dog, life had been instantaneously destroyed by pithing, and collections were made immediately after from the jugular vein and crural artery.No time was allowed for the effect of post nzortein formation of' sugar in the liver to influence the blood. The results obtained by this method were as follow : crural artery, -799, -791 ; mean, "795. I n order, however, to obtain evidence to which no exception could be taken, Dr.Pavy adopted another method of procedure, which he was enabled to do just prior t o the meeting of the society, from having a restriction previously imposed under the Vivisection Act removed. This enabled him to collect the blood under the natural conditions of life, both from the carotid artery and the jugular vein. The animals operated upon were placed under an anmsthetic, during which time the vessels were exposed and a thread placed loosely round each.After they had regained tranquility, and the effect of the anxsthetic passed off, the vessels were drawn forward and openings made into them to allow of the simultaneous escape of blood. So quietly and painlessly was this operation of collection performed, that the animals themselves manifested no signs of consciousness of what was taking place.The analyses of the blood obtained in this manner were commenced before coagulation had time to occur, and the results were as follow : No. 1, carotid artery, 0806, .817; mean, -811. Jugular vein, -503, -788; mean, 798. No. 2, carotid artery, -854, *873 ; mean, -863. Jugular vein, 863, 896; mean -879.From these figures it is clearly evident that no material difference exists in the amount of sugar contained in arterial and venous blood. Jugular rein, -793, -791 ; mean, ,792 SPONTANEOUS DISAPPEARANCE OF SUGAR FROM BLOOD. Turning to the third part of his subject, viz., the spontaneous dissppearance of sugar from blood after its removal from the system, Dr.Pavy gave the results of a series of analyses ho had conducted, and which are as follows :- No. 1. No. 2. No. 3. Taken immediately after death Taken immediately after death .. after 1 hour ... Taken immediately after death .. after 1 hour ... ,, ,, 23 hours No. 4. Taken immediately after dt& .. after 1 hour ... .. 24 hours ... No. 5. Tacen immediately after death .. after 1: hours ..... after 1 hour ... . . . . . . mean -786 . . . . . . ,, ,739 . . . . . . ,, *700 . . . . . . ,, -670 . . . . . . ,, -766 . . . . . . ,, ,751 . . . . . . ,, *285 . . . . . . :, ,786 . . . . . . ,, -728 . . . . . . ,, *302 . . . . . . ,, -921 . . . . . . ), a793 Dr. Pavy poiuted our thut there was nothing new in the suggested discovery that a gradual destruction of sugar takes place with blo~il after its removal from the system. He himself had brought tho fact before thenotice of the Royal Society so far back as 1855, when he stated that under the changes of the decomposition of blood normal animal glucose is very readily metamorphosed. The rapidity of the metamorphosis depending on the activity of the decomposition of the animal substances present. I n conclusion the author stated that the evidence adduced in this communication shows that the results which Bernard has obtained by the experimental modus operandi he has been recently employing are erroneous, and, consequently, the inferences he has drawn from them are equally in error. The cause of truth and the interests of science demand that what he has recently been advancing should be eliminated from physiological literature.