b. Amongst birds, I have found the round cells in Falco albicillus, Cuculus canorus, Turdus varius, Perdix saxatilis, and Sylvia hortensis. They were in larger or smaller quantity, from 4 to 10-1000ths of a line in size, with dark golden yellow granules which were evidently nothing but metamorphosed blood globules. This was very distinctly shown in Turdus musica, since here the cells occurred with unchanged blood globules. Everywhere these cells eXperienced a trans ition, partly into brown and black granule cells, partly into colorless granulated cells.
c. Amongst the Reptilia. In the scaly Reptilia, amongst which I have only ex amined Anguis fragilis and Coluber austriacus, I have seen no cells with unchanged blood globules ; but in the Anguis I found pale yel low, brown, and black granule-cells, which were, as in birds, of from 6 to 10-1000ths of a line in diameter. Transitions of these into faintly yellowish and colourless granule-cells were also present in considerable number, being almost as frequent as the ordinary pa renchyma cells in the spleen-pulp. The Co luber austriacus certainly exhibited an effit sion of blood in the parenchyma of the spleen, but no changes of the blood corpuscles. The naked amphibia offered a striking contrast. Amongst them I examined Rana temporaria and esculenta, Bombinator igneus, Hyla ar borea, Bufo cinereus, Alytes obstetricans, Salamandra maculata and atra, Triton igneus, tmniatus, and cristatus. The cells with blood globules were better seen in these than in any other animals. This was especially the case in Triton, Bombinator, and Rana, in which 5, 10, 20, and more blood globules, with dis tinct nuclei, were frequently seen occupying a plainly nucleated cell of 6 to 12-1000ths of a line in diameter. The size of the blood globules in these cases allowed their meta morphoses to be followed through all stages, as is represented in fig. 532. At first they were round, of an intense yellow, and less easily altered by water ; then they contracted themselves yet more together, assumed a golden yellow or brown yellow colour, and were no longer assailed by water ; finally, they became colourless, or experienced a transition into black granules, while they generally. also fell asunder into smaller granules. In this manner golden and brownish yellow granule-cells (fig. 532. 1.) arise from the cells with unchanged blood globules (fig. 532. 2, 3, 5.), and finally they experience a transition into colourless granule-cells (fig. 532. 4.), or exist for a longer time as black pigment cells.
d. In fishes I have recognised the same con ditions as in the naked amphibia, only they were not so brilliant. The cells with blood globules were very distinctly seen in Salmo fario, Cyprinus carpio and brama, Tinca chry sitis, Esox lucius, Perca fluviatilis, Coregonus muraena, and Gadus Iota. In Anguilla flu viatilis, Aspius alburnus, Chondrostoma nasus, leucocephalus, &c., they were less plainly seen; nevertheless, cells with shrunken blood cor puscles, or aggregates of such, occurred also in these. In all fishes these structures be come converted partly into colourless granule cells, partly into black pigment.cells and pig ment masses, which finally often lose their colour.
The place where the changes of the blood corpuscles above mentioned occur can be demonstrated in some amphibia to be the bloodvessels. Thus, in Triton igneus, the spleen is at its margins tolerably transparent, and here one frequently comes upon the cells which contain blood corpuscles, occupying the capillaries in a row one after another ; and here we are also able to drive them into the larger venous channels by pressure, so that one of these is often filled by a consider able streak, consisting entirely of these alto gether characteristic elements. Whether this occurrence is a rule in the Triton, and whether it obtains in other amphibia, I am unable to certify. Yet I may communicate that, in the Triton, frog, toad, and Salamandra atra, I have found these cells containing blood corpuscles even in the trunks of the splenic vein and vena port ; while in Bufo cinereus, Triton igneus, and Salamandra, I have found them in the hepatic branches of the vena portw, even to its capillaries ; and in the latter animal, even in the inferior cava and the heart. In any case, these facts may be con sidered as conclusive of tbe not unfrequent occurrence and formation of the cells in ques tion within the bloodvessels of the spleen ; although it can scarcely be added that they are not probably also formed in the extra vasated blood. In certain genera of fishes, as in Tinca, Esox, Perca, the cells which contain blood corpuscles, and their metamorphoses, are seen included in round delicate-walled vesicles of from 1-40th to 1-16th of a line in diameter ( fif.z. 533.). which for the most part sit on the ramifications of the splenic arteries, either laterally on the vessels, or on the points where they divide ; and which are connected with the sheath or exterior membrane of the same ; or, in other words, are nothing else than pouckings of the same. How these ve
sicles are developed I have not determined, yet T. can scarcely doubt that they have the import of false aneurisms, and owe their origin to a teming of the inner and middle tunics, and to a protrusion of the tunica ad ventitia, together with the sheath of the ves sels (if the latter texture can be supposed to exist here). The similarity of these vesicles with the Malpighian corpuscles of the mam mals seems to be especially worthy of men tion. After the description already given of the relation of the Malpighian corpuscles to the arteries, it is unnecessary to explain in de tail, that the correspondence of both in re spect of their site is very great. But, in re spect of their contents a similar resemblance is sometimes exhibited, when, as in the cysts of fishes, the cells with blood corpuscles have all undergone a transition into colour less cells, or the Malpighian corpuscles con tain effused blood. By pondering upon these circumstances, one might almost come to the idea of regarding the cysts of fishes as Mal pighian corpuscles, or the Malpighian cor puscles of mammals as false aneurisms of the splenic arteries ; but in my opinion either of these vievvs would be altogether erroneous. For although blood is often present in the Malpighian corpuscles, yet this appearance is much too seldonz to allow of our explaining their contents as arising out of altered blood. And as regards the cysts of fishes, they are alto gether absent from many fishes, and, where they are present, often undergo a cretifica tion, or are changed into concretions ; while they occur in other organs, as for instance in the kidneys : facts which have little confor mity with the constant occurrence of the Mal pighian corpuscles. In others of the fishes previously mentioned, no vesicles can be re cognised in the spleen; on the contrary, in many genera, the blood corpuscles obtained in different conditions of their metamorphosis are seated together in roundish heaps of a more or less definite outline, and of a size which equals that of the vesicles : these are evidently nothing else than extravasations of blood. The numerous circumscribed red or brown points which occur in the spleen pulp of all fishes, are nothing but the self-decom posing blood globules ; and they are, as above mentioned, either free or arranged in masses which are included in vesicles. In the scaly reptilia, birds, and mammals, it is very dif ficult to state_with certainty in what part of the spleen the formation of the cells which contain the blood corpuscles and their meta morphosis occurs. At first I thought of the hollow interspaces with which the vein of the spleen begins ; only these spaces, as will be shown hereafter, do not in the least obtain in the human subject in the form which has been hitherto attributed to them. Or the branches of the veins, which are always large, might easily be regarded as the locality, provided that the occurrences above mentioned be not regarded as extravasations. With regard to this question direct observation teaches us as fol lows. In the capillaries and arteries of the sp leen in mammalia no changes of the blood corpuscles exist ; so that the only question is, whether the blood corpuscles, which con stantly occur in the spleen-pulp, and here un dergo their metamorphoses, are situated in the commencements of the veins ; or whether they occupy spaces newly formed by the ex trusion of the blood. Much may be adduced in support of the first of these views. Thus, it is scarcely possible to suppose that extra vasations of blood in such extraordinary quan tity constantly occur in the spleen; then it may also be mentioned that pigmentary gra nule-cells, such as are developed in the spleen from the blood, may also be found in blood vessels exterior to the spleen, which seems to speak for their being situated within the ves sels in the case of the spleen itself. I have myself formerly found scattered pigment-cells in human blood * which I can now only re gard as granule-cells from the spleen. Ecker has also seen t in the splenic veins of the calf, cells containing blood corpuscles like those in the spleen. And, lastly, Meckel has also found black pigment-cells in the blood of a woman whose spleen abounded in them. Finally, we may recollect, that in the amphibia the cells in question are certainly situated in the vessels. But, on the other side, it must not be forgotten that in the spleen of fishes metamorphoses of the extravasated blood take place, and that also portions of the extravasations enter the vessels, and that it is possible the pigment-cells in the blood may thus originate ; finally, that the masses of blood in the spleen-pulp are scarcely de fined with the sharpness which they would possess even in veins with very delicate coats. In this state of things it is much better to abstain from giving a definite decision ; or if one be absolutely required, to attribute the metamorphoses of the blood in the spleen of mammals to both the localities mentioned.