Further Experiments on the Spleen

XI. Further Experiments on the Spleen. By Everard Home, Esq. F. R. S. Read February 25, 1808. The results of the experiments already brought forward having established the fact that fluids received into the stomach, when the pylorus is closed, pass through the spleen into the circulation of the blood; it became an object to determine, by experiment, whether this takes place when the parts are in a natural state. The ass appeared, on many accounts, the best subject for this purpose, and as it is made use of to teach the veterinary pupils the anatomy of that tribe of animals, I applied to the Professor for permission to make my experiments in the theatre of the college. This was granted me in the most obliging manner; the subjects were also supplied by the College, and Mr. Sewell, the assistant Professor, gave me his personal aid with a degree of zeal and ability I have rarely met with, and have much pleasure in acknowledging. In making the following experiments, I had the assistance of Mr. Sewell, Mr. Brodie, Mr. William Brande, and Mr. Clift. Experiment 1. An ass, which had been kept twenty-four hours without hay, to prevent the liquor that was to be poured into its stomach from being soaked up and retained there, on the evening of the 3d of December, 1807, had a drench given it, consisting of half a pint of the spirituous tincture of rhubarb, diluted in half a pint of water. On the morning of the 4th, this was repeated at eight o'clock, and again at twelve. At two o'clock the animal was pithed, so as to destroy its sensibility, and before the circulation was entirely stopped, six ounces of blood were taken from the splenic vein into a graduated glass measure, and a similar quantity was taken from the left auricle of the heart, into a vessel of the same kind; these were allowed to coagulate and separate their serum. The spleen was large and turgid; upon making sections of it, the cells were found to be very numerous; and towards the great end and near the edge, they were particularly distinct to the naked eye. The cut surface had a strong smell of rhubarb, and when it was applied to white paper wetted with the alkaline test, an orange tinge was produced. This was strongly contrasted by a stain made in the same manner with a section of the liver, which had no such tinge, nor did the liver give the slightest smell of rhubarb. Infusions were made of the spleen and liver under similar circumstances; these were strained off into separate glasses, and tested by the alkali. The urine was tested in the same way. The serum, from the different portions of blood, was also poured off into separate glass vessels, to which the test was added. In nineteen hours after the blood had been taken from the veins, they were all compared together. The urine had so deep a tinge, that it nearly resembled the pure tincture of rhubarb in appearance; the others had a tinge, although in very different degrees; the quantity of rhubarb they contained was estimated by adding tincture of rhubarb to alkaline water so as to produce corresponding tints. The infusion of spleen had a tint equal to sixty drops of tincture of rhubarb in two ounces of alkaline water; the serum of the splenic vein, to fifteen drops; the serum from the left auricle of the heart, to three drops. The infusion of the liver gave no orange tinge, but had it not been obscured by the red particles of the blood, it must have been equal to that of the serum from the auricle. The connecting membrane between the stomach and spleen was attentively examined, very few absorbent vessels were seen, and these were not in a turgid state, they were traced to the chain of glands situated near the edge of the spleen, which receive the absorbents of the stomach, but none were detected passing beyond the glands, nor did the glands admit quicksilver to pass through them towards the spleen. Exp. 2. The former experiment was repeated upon another ass, with similar results, but less strongly marked; the cause of this difference was explained by the abdominal viscera being in an inflamed state. The urine was less impregnated with rhubarb, the infusion of the spleen had a lighter tinge, and the serum of the splenic vein had it in a still less degree; but evidently exceeding that of the serum from the vena cava inferior opened just below the diaphragm, which was substituted for the left auricle of the heart, with a view to vary the experiment. Exp. 3. The same experiment was made on a third ass with similar results. Exp. 4. An ass that had been kept four days without water, and two without solid food, on the evening of the 8th of January, 1808, had a ball given it, containing half an ounce of powdered rhubarb; on the 9th, at seven o'clock in the morning, this was repeated; a third was given at nine o'clock, and a fourth at twelve. At two o'clock the ass was pithed, and four ounces of blood were taken from the splenic vein, and the same quantity from the left auricle of the heart. The spleen was found contracted to half the size of those in the former experiments; when cut into the cells were small, and it required a magnifying glass to see them distinctly. The substance was compact, and bore a near resemblance to a portion of liver; so that in this state the blood vessels, particularly the veins, must have been much contracted in their diameters. The stomach contained about two ounces and a half of a gelatinous substance mixed with rhubarb, the small intestines were nearly empty, but the caecum and colon contained several quarts of water, in which the rhubarb was more evident both to the sight and smell, than in the stomach. The absorbent glands upon the edge of the colon were ranged in two rows, one on each side of the great vein, and were exceedingly numerous. In the space between these rows of glands, in some places twenty trunks of absorbent vessels could be readily counted, of a very large size. The urine was impregnated with rhubarb, so as to acquire an orange tinge from the addition of the test; but the infusion of the spleen, and the serum of the different portions of blood, did not contain it in sufficient quantity to have the colour heightened by alkali. Exp. 5. The last experiment was repeated upon another ass. Two ounces of blood were taken from the splenic vein, two from the large vein of the colon, and two from the inferior vena cava in the lower part of the loins. The spleen had the same appearance as in the last experiment. The stomach contained nearly a pint of moderately solid contents, in which the rhubarb was very evident. The small intestines were nearly empty; but the caecum and beginning of the colon contained several quarts of liquid, strongly impregnated with rhubarb. The absorbent glands and vessels had the same appearance as in the former experiment. The urine when tested was found impregnated with rhubarb. The portions of serum of the blood taken from these different veins, when tested by the alkali, appeared to be very much alike; at least that from the splenic vein was not more tinged than the others. Exp. 6. Having been informed by Mr. Sewell, that spirituous liquors given in large quantities to horses, produce inflammation of the brain, and sometimes death, and this information having been in some measure confirmed by an ass in a weakly state, that had taken half a pint of the spirituous tincture of rhubarb in the evening, dying in the night, I thought it right to make a comparative experiment with the infusion of rhubarb, to determine whether the result would be the same as with the tincture. February 9, 1808. An ass had a pint of infusion of rhubarb given to it in the evening; the same dose was repeated at six o'clock in the morning of the 10th; and again at nine o'clock, and at twelve. At two o'clock the animal was pithed, and two ounces of blood were taken from the splenic vein, two from the vein of the colon, and two from the inferior vena cava in the lower part of the loins. The spleen was found turgid, and large; when the cut surface was rubbed on white paper, the orange tint was very evident without any test applied to it, particularly so, when compared with a similar stain made by a section of the liver, in which there was no such tinge. In the stomach and duodenum, the rhubarb was found in large quantities; but none was met with in the caecum. The urine was impregnated with rhubarb, the orange tint upon the application of the alkali being very distinct. At the end of twenty hours, the serum of the splenic vein had a tinge equal to four drops of the tincture of rhubarb in two ounces of alkaline water; that of the vein of the colon and vena cava was less distinct. The effects of the infusion of rhubarb on the spleen, the serum of the blood and the urine corresponded exactly with that of the tincture in the former experiments, but was in a less degree of intensity. In the course of these experiments, an attempt was made to ascertain whether the blood in the splenic vein has a greater proportion of serum than in the other veins of the body, and the general results were in favour of such an opinion; but it will appear, from what follows, that the quantity of serum separated in twenty-four hours, is by no means a just criterion of the proportion, which the blood contains. Experiment 1. Three ounces of blood from the arm of a healthy person were received into a graduated glass vessel, previously cooled to the temperature of $32^\circ$, three more into a second glass of the temperature of $50^\circ$, and three into a third at $70^\circ$. The three glasses were brought into a room, the temperature of which varied from $40^\circ$ to $50^\circ$. At the end of nineteen hours, the serum was found in the following quantities. In the glass at $32^\circ$ 9 drams. \[ \begin{align*} 50^\circ & \quad 11 \\ 70^\circ & \quad 10 \end{align*} \] The blood did not flow so freely into the glass at the highest temperature, as into the other two. Exp. 2. This experiment was repeated, and the serum examined at the end of forty-three hours. In the glass at $32^\circ$ 12 drams. \[ \begin{align*} 50^\circ & \quad 12 \\ 70^\circ & \quad 13 \end{align*} \] Exp. 3. It was repeated, and the serum examined at the end of 67 hours. In the glass at $32^\circ$ 11 drams. \[ \begin{align*} 50^\circ & \quad 11\frac{1}{2} \\ 70^\circ & \quad 11\frac{1}{2} \end{align*} \] Exp. 4. It was repeated, and the serum measured at the end of ninety hours. In the glass at $32^\circ$ 11$\frac{1}{2}$ drams. \[ \begin{align*} 50^\circ & \quad 13 \\ 70^\circ & \quad 10\frac{1}{2} \end{align*} \] The blood did not flow so readily into the glass at the highest temperature as into the other two. From these experiments, it appears that the serum separates in larger quantity, when the blood is received into a vessel at the temperature of $70$ degrees, than at $50^\circ$ or $32^\circ$: this, how- ever, is prevented from taking place by the blood not flowing readily from the vein. From the experiments on the spleen contained in this, and the foregoing Paper, the following facts appear to have been ascertained. That the spleen is met with in two very different states, one which may be termed the distended, the other the contracted, and that in the one its size is double what it is in the other. In the distended state there is a distinct appearance of cells containing a limpid fluid, distinguishable by the naked eye; in the contracted, these only become distinct when seen through a magnifying glass. The distended state takes place when the stomach has received unusual quantities of liquids before the animal's death; and the contracted state, when the animal has been kept several days without any drink before the spleen is examined. That the trunk of the splenic vein (of the hog) is more than five times the size of the trunk of the splenic artery. That when the pylorus is secured, coloured liquids pass from the cardiac portion of the stomach into the circulation of the blood, and go off by the urine; and while this is going on, the spleen is in its most distended state, and the colouring matter is found in its juices, although it is not to be detected in those of the liver. The colouring matter cannot therefore be conveyed to the spleen through the common absorbents of the stomach, which lead to the thoracic duct. That when the pylorus is open, the colouring matter under the circumstances abovementioned is equally detected in the spleen. That when the spleen is in this state, the blood in the splenic vein has its serum more strongly impregnated with the colouring matter, than that of the blood in the other veins of the body; and when the stomach is kept without liquids, although colouring matter is carried into the system from the intestinal canal by the ordinary channels, no particular evidence of it is met with in the spleen or its veins. That the caecum and the portion of the colon immediately beyond it, is found (in the ass) to be at all times filled with liquids, even when none has been received into the stomach for several days, and there is a greater number of absorbent vessels for carrying liquids from the colon into the thoracic duct, than from any other part of the body. The colon is therefore a reservoir, from which the blood vessels are occasionally supplied with liquids. Mr. Sewell informs me, that the same observation applies in a still greater degree to the horse. That coloured liquids taken into the human stomach, under some circumstances, begin to pass off by urine in seventeen minutes, continue to do so for some hours, and then disappear; they are again met with in the urine, after the colouring matter is known to have arrived at the great intestines, by its passing off by the bowels. From the above facts, the following conclusions may be drawn. That the liquids received into the stomach beyond what are employed for digestion, are not wholly carried out of it by the common absorbents of the stomach, or the canal of the intestines, but are partly conveyed through the medium of the spleen into the circulation of the liver. The vessels which communicate between the stomach and the spleen have not been discovered; but if it is proved that the colouring matter of the contents of the stomach, is met with in greater quantity in the spleen and in the vein which goes from that organ to the liver, than in the other veins of the body, there appears to be no other mode in which it can arrive there, but by means of such vessels; and the two different states of the spleen, which correspond with the quantities of liquids that pass from the stomach, are strongly in favour of the existence of such a channel. This communication between the cardiac portion of the stomach, and the spleen, will explain the circumstance of those who are in the habit of drinking spirituous liquors having the spleen and liver so frequently diseased, and the diseases of both organs being of the same kind. This organ is not essential to life, its office being of a secondary kind; but when it is materially diseased, or entirely removed, digestion must be disturbed. The extent to which this takes place, cannot be accurately known from experiments on quadrupeds, and the instances in which the human spleen has been removed have not been attended to with sufficient accuracy to afford an explanation of the effects that were produced on the stomach.