If, after these remarks, we take a glance at the import of the Malpighian corpuscles, we shall be compelled especially- to ask ourselves, first, whether they are the beginnings of the lymphatics, or in any other way connected with them ? and, secondly, whether they have the import of glandular vesicles ? A connection of the Malpighian corpuscles with the lymphatics was a belief of many anato mists in earlier times, and in our own days has been recently upheld by Giesker, Huschke, Gerlach, and Poelmann. The acceptors of such a theory rest mainly on conjecture, but partially also on facts. Amongst the latter, there may be mentioned — 1. The cor respondence of the cells in the Malpighian corpuscles with the lymph corpuscles. But we must remember that cells which cor respond with the lymph corpuscles occur in many other situations where no such connec tion with the lymphatics can be imagined, as in the spleen-pulp itself, in the pancreas, in the salivary glands, the glands of mucous mem brane, the thymus, thyroid, &c. 2. Huschke adduces the similarity of the spleen vesicles with the whitish granules of the lymphatic glands, which are dilatations of the lymphatic vessels thernselves. Against this it need only be objected, that this latter is a pure fiction of Huschke's, and that even were it as he states, no conclusion concerning the nature of the Malpighian corpuscles could fairly be deduced from it. I have yet further to men tion, that, according to an oral communica tion of Ecker which was made to me many y ears ago, and recently repeated, concerning the splenic vesicles of the mammalia, processes and pedicles exist which are neither blood vessels nor partitions, and, therefore, may be ly mphatics, —a view with which Poelmann's and Gerlach's recent statements are some what in unison. The former of these two* says that he followed the thoracic duct even to the Malpighian corpuscles, with which it became connected ; but he does not specify more exactly the nature of this connec tion. The latter says that it has often seemed to him as if the neighbouring Mal pighian corpuscles communicate with each other through special tubes; that he has been led to this belief by the circumstance that when the vesicles are compressed, their con tents are expelled in definite directions, which a closer examination shows to be canals, the coats of which tolerably resemble in texture those of the Malpighian corpuscle ; and that it is thence clear that the corpuscles communicate with a system of tubes which can scarcely be imagined to be any thing else than the lymphatics. And thus, if the Mal pighian corpuscles are dilatations of the lymphatics, they may possibly be commenced as simple varicose swellings, or, what is more probable, as lateral productions of these vessels. I acknowledge that I am unable to verify this fact last adduced, or to subscribe to this connection of the Malpighian cor puscles with the lymphatics. In my researches I have given an attention to this point con formable to its great importance ; and although I have not seen the commencement of the ly mphatics in the spleen, yet I have so far come to a positive conclusion, that I am con vinced of the complete closure of the Mal pighian corpuscles. What Gerlach states of the tubes into which the contents of the cor puscles are forced, is altogether erroneous ; such tubes nowhere exist. Gerlach appears to have been misled to this opinion by the fact, that when a corpuscle is burst by pres sure, the contents rush out at several points, and are then effused in the shape of long and small streaks in the surrounding tissues. If the comrnencements of such a streak were not observed, it might easily be regarded, from its always taking a radiating course from the Malpighian corpuscle to which it is united, as a canal comniunicating with the same especi ally when a longer pressure applied' to the corpuscles has elongated these stripes by con tinually forcing out the contents. The pro cesses which Ecker has described on the Malpighian corpuscles, and which are not bloodvessels, probably belong to the same category as the artificial products mentioned above ; or, if this is not the case,it is possible that they are small trunks of nerves, which are frequently present in the neighbourhood of Malpighian corpuscles, and which, from reasons that will be hereafter mentioned, are exceedingly difficult to recognise as being what they really are. I therefore maintain,
quite plainly' and definitely, that the Malpighian corpuscles are closed capsules, and stand in no connection at all with the lymphatics.
If this be so —and the structure of the Malpighian corpuscles, which altogether differs from that of vessels, corroborates the fact — it is next demanded may not the Malpi ghian corpuscles be glands ? If by "glands" be meant the word in its ordinary sense, I answer with a decided "no ;" for these alto gether differ from the known simple shut glandular sacs of the ovary, thyroid, thymus, and supra-renal capsules, and possess neither a structureless membrana propria (limitary membrane, or basement membrane) nor an epithelium. On the contrary, in my opinion, they correspond with the spaces filled with cells in the lymphatic glands, and with the sacs of the glandulm solitarim and agminatm of the intestine. Here and there hollow spaces exist, which possess a covering of white fibrous tissue, are completely inclosed, and contain in their interior no trace of epithelium, but only a coherent mass of nuclei and cells, together with some fluid; we might call these " vesicular glands," recol lecting at the same time that they possess the function of the real shut glandular vesicles, although their anatomy essentially differs. Although the discussion of the former ques tion does not belong to this part, yet I will add, that, in reality, there is much to indicate that the structures in question constitute a kind of shut glandular vesicle ; and that, con sequently, there is nothing to prevent their being reoarded as glandular vesicles.
5. The red spleen substance, the spleen-pulp, the parenchyma of the spleen (substantia ru5ra, pulposa, parenchyma lienis), is a soft reddish mass, which fills up all the interstices between the larger partitions and the stronger vessels, and on section of the organ is easily scraped off or squeezed out. It consists essentially of three constituents ; which are, fine bloodvessels, parenchyma cells of the spleen, and small partitions or fibres. To these constituents is so frequently added, both in man and animals, extravasated or coagulated blood in various metamorphoses, that one is ahnost forced to designate it a normal constituent. According to the pre dominance or diminution of the latter in. gredient, or according to the greater or lesser distention of the bloodvessels themselves, the spleen-pulp appears sometimes altogether of the colour of the blood, at others of a clearish red, with a greater or lesser tendency towards whiteness.
The following remarks apply to the mi croscopic appearances of the constituents of the pulp, the vessels only excepted, which will be described hereafter. The fibres of the pulp are of two kinds. The one kind, which may be named " small or microscopic partitions " (" microscopische balkchen"), are quite analogous to those larger partitions ("balken") which are visible to the naked eye; they are also of the same structure, except that in the lower animals they often contain more muscular fibres than the latter. Their diameter is variable, from 5 to 10-1000ths of a line; their frequency and quantity also vary in different situations, and amongst different creatures. In the human subject I find them to be fewer and broader than amongst other mammalia, and exactly like the larger partitions in structure; while in the ox, sheep, &c., they occur frequently, are more delicate, and are remarkable by their purely muscular structure. The other fibres of the pulp are evidently processes from the sheaths of the larger vessels ; they greatly predomi nate in quantity, and appear chiefly in the form of delicate membranes of an indistinctly fibrous structure, and without any mixture of elastic fibres, vvhich seem to connect the capillaries to each other. Whether they take the form of small partitions— in which case they could not be distinguished from the small trabecula —is at present unddcided. In animals, these membranes are also present on the veins ; but of this more will be said hereafter, in speaking of the vessels.