As regards the time at which the blood globules experience their dissolution in the spleen, nothing definite can at present be said ; but my theory appears at least to pre suppose, that this process especially comes to pass some time after the reception of nutri ment, since I have found the spleen of the greatest size in animals at about the time of five to twelve hours after eating, the same time at which the visible changes of the blood globules were most marked. The cause of this phenomenon seems to be, that the vo. lume of the blood is increased after each time of taking food, and especially that a great num ber of new cells enter from the chyle. And if an equal weight is to remain in the organism, then, on the other hand, just as many elements of the blood must be dissolved, as there have new ones entered into it ; and this is ex actly what happens in the spleen. Besides, I am not anxious to maintain that the spleen may not become distended, and blood glo bules undergo dissolution, at other times than those just mentioned ; probably the con ditions of the liver have also a great influence upon the events in the spleen, so that in hypermmia of the liver, the spleen becomes also distended ; and so likewise the nervous sys tem may be interested therein. Beclard, who has also found many variations in the blood globules contained in the blood of the splenic vein, is unable to assign any definite cause for these varieties, and only remarks, that in the case of a blood rich in blood globules, the amount of these lost in the spleen was greater than in the opposite case. So that it must be left to the future to bring to light the more special relations of the dissolution of the blood globules in the spleen.
I have hitherto said nothing concerning the function of the Malpighian corpuscles of the spleen. I do not regard their function as at all a peculiar one, since (1.), in many animals, as fishes and naked amphibia, these corpuscles are ab sent ; 2. their constituents exactly correspond with those of the parenchyma of the spleen.
I believe that the parenchyma-cells and the cells of the Malpighian corpuscles play exactly the same part, although I am just as little able as my predecessors to say with certainty what this is. If they are not subservient to the formation of a special fluid vvhich takes a part in the solution of the blood corpuscles, I should be almost inclined to ascribe to the parenchyma-cells the mechanical use of form ing in the first place a soft parenchyma in which the minute vessels can extend at their pleasure ; and nextly, that they, as well as the elements of the Malpighian corpuscles, are simply expressions of the fact, that the spleen, as a highly vascular organ, is everywhere permeated by a fluid which is very rich in plastic matters. At the same time, it may be imagined that all these cells elaborate the fluid in which they are soaked, and after a certain kind of assimilation, again part with it, and through the blood and lymph vessels transmit it to the general circulation. The
swelling up of the Malpighian corpuscles after the use of food is quite consonant with this notion. But whether this fluid is of a pe culiar nature, and of different properties from that of other organs, we can only know from future cheraical researches ; and then only can it be determined, whether or no we are to ascribe to it a special signification.
If the spleen be the only or even the chief organ in which blood globules undergo their dissolution, in either case the part which they enact in the organism is by no means the subordinate one which many have hitherto considered it ; but one which is very full of import. And the results affbrded by vivisec tions and by pathology are by no means so contradictory to this expression as they are generally maintained to be. It is true that the spleen of animals may be excised without causing their death, a fact which I have my self repeatedly witnessed ; it is also certain, that men can live without spleens, or with spleens completely atrophied, or rendered functionally useless by degeneration ; nay, in many cases, may live without any disturb ance at all,—a circumstance which is also true of animals. But what does this prove ? Nothing at all ; for if the spleen fails, then indeed other organs undertake its functions, and discharge them vicariously for it. Pro bably in these cases the blood globules un dergo dissolution in the general mass of the blood, or possibly in the liver. But if this be so, the spleen is surely not therefore devoid of import or function. With equal correctness might we say, that one kidney is superfluous, because in certain cases an hypertrophied kidney enacts the part of both ; or might re. gard kidneys generally as devoid of import, because certain rare instances of misdevelope ment are narrated, in which the skin or the thoracic glands have undertaken the excre tion of the urinary constituents. If the spleen is not the only organ in which blood cor puscles undergo dissolution, it is possible that these are destroyed in some small quantity in the capillaries of all the organs of the body, Many observers, as Lecanu and Letellier, and more recently J. Beelard, have found a dimi nution in the quantity' of blood corpuscles in the venous blood generally, although others have denied this. If this be the case, it con firms such a supposition, and would effectually explain the results of extirpation. In any case thus much is certain, that they afford no grounds for regarding the spleen as devoid of signification. Finally, we may remark in ad dition, that not unfrequently extirpations of the spleen give rise to considerable disturb ances, and especially of the biliary secretion ; a fact which very well corresponds with my supposition that the colouring matter of the bile wises from the hmmatin set free in the spleen.