SPLEEN. 



781 



with the cells of the spleen vesicles ; the 

 characteristic appearances of which are their 



Fig. 530. 



n. 4Sf^ 



Parenchyma- cells from the spleen of the Ox, magnified 



350 diameters. 



a, Smaller cells ; b, cells of medium size ; c, free nu- 

 clei ; d, largest cells. 



roundness, their size from 3 to 5-1000ths 

 of a line their paleness, and their dark 

 nucleus (Jig. 530. b). On the other hand, 

 smaller and larger corpuscles also occur in 

 the spleen-pulp, which are never met with in 

 the Malpighian corpuscles. The former are 

 small round corpuscles, somewhat larger than 

 blood globules. They are seen in one of two 

 states : either they exhibit a membrane and 

 nucleus inseparable from each other, and 

 thus, apart from their colour and somewhat 

 lighter outline, resemble blood globules ; or 

 they are free nuclei, in which no nucleoli are 

 visible. But only a few of these are free 

 nuclei, for by the application of saliva or a 

 little water a membrane starts into view, 

 either completely enclosing them, or limited 

 to one side (fig. 530. a). The nuclei, which 

 thus appear as something separate from the 

 membrane, have always the dark appearance 

 of those cells the two parts of which are 

 inseparable from each other ; so that the 

 appearance of these latter would seem chiefly 

 dependent on the nucleus. With these small 

 and quasi-developing cells, one also meets 

 with free nuclei ; and careful manipulation of 

 the preparation shows these to be in general 

 more numerous than in the Malpighian cor- 

 puscles (fig. 530. c}. The larger named cor- 

 puscles are partly pale cells of 7-1000ths of a 

 line in size, with one or two nuclei); or granule- 

 cells of 4 to 6-1000thsof a line, and which may 

 be described as " the colourless granule- 

 cells" (fig. 530. d) : both of these are more 

 frequent than in the Malpighian corpuscles. 

 The spindle-shaped or fusiform cells which 

 Hessling mentions do not belong to the 

 normal constituents of the spleen-pulp, and 

 are nothing else than epithelium cells of the 

 splenic arteries (fig. 534. b), which in ma- 

 cerated specimens of the human spleen, and 

 in preparations where the vessels have been 

 cut through, easily get into the pulp, and 

 give rise to the delusive appearances of the 

 so-called fusiform cells. The comparative 

 examination of this part of the spleens of 

 many animals confirms what has been al- 

 ready stated of the elements of the Malpi- 

 ghian corpuscles ; namely, the elements of the 

 pulp vary greatly, since sometimes the nu- 

 clei, sometimes the smaller cells, sometimes 

 the greater cells, predominate. And in this, 

 as in the former case, I conclude therefrom 

 that a continuous process of cell growth ob- 

 tains in the spleen, by which new cells are 



formed around nuclei, and old ones dis- 

 appear. 



The quantity of parenchyma-cells of dif- 

 ferent kind and shape, and of free nuclei 

 which must be reckoned with these, is a very 

 considerable one ; so much so, as to con- 

 stitute nearly one half of the whole red 

 spleen substance. These do not lie collected 

 in large heaps, but constitute small irregular 

 groups of different size, which occupy the 

 interspaces formed by the partitions of all 

 sizes, the vessels, and the Malpighian cor- 

 puscles. The best method of representing 

 this disposition is to regard each part of the 

 pulp, which is included in a large mesh by 

 trabeculse visible to the naked eye, as con- 

 stituting in a small form what the spleen 

 itself is in a larger. The microscopic par- 

 titions and fibres and the finest vessels thus 

 exhibit the same relations as the larger par- 

 titions and vessels ; while the small nests of 

 parenchyma-cells answer to the large homo- 

 geneous masses of red pulp which are visible 

 to the naked eye. There are nowhere any 

 special coats which include these cells, but 

 they may be seen everywhere placed imme- 

 diately on the sheaths of the vessels, the par- 

 titions, and the membranes of the Malpighian 

 corpuscles. In the above delineation of the 

 parenchyma-cells, those of man and of the 

 higher mammalia have especially served as 

 the model: but in general a complete simi- 

 larity obtains in other animals ; and it is 

 only here and there that any specialities 

 show themselves. In many animals thus, 

 for instance, in amphibia the spleen has 

 often, though not always, very beautiful pa- 

 renchyma-cells with large nuclei : in birds, 

 and m the scaly Reptilia, granulated and 

 somewhat dark cells are for the most part 

 more frequent. In the hedgehog, rabbit, and 

 guinea-pig, some cells, which are altogether 

 peculiar, occur in company with the ordinary 

 ones. In both the former of these I saw, 

 here and there, large round cells from 10 to 

 16-1000ths of a line, with three, four, to ten 

 or more nuclei, which often lay so closely 

 together in the middle of the cell that they 

 appeared to make up a mulberry-like mass, 

 like certain large cells which one finds in the 

 marrow of young bones. These cells were 

 by no means uncommon, but gradually dimi- 

 nished in'size towards that of the parenchyma- 

 cells. In the guinea-pig occur round cells, 

 in large quantity, of 48 to 60-10000ths of a 

 line, which contain one or seldom two round 

 granules of a dark contour ; and their nu- 

 cleus, not always very distinctly visible, is 

 very plainly seen on the application of acetic 

 acid; while, at the same time, the dark 

 granules often disappear. 



The blood effused in the spleen-pulp, as well 

 as the metamorphoses of the blood globules in 

 the same, demand the greatest consideration 

 both in respect of anatomy and physiology. I 

 believe myself to have been the first who* 

 directed attention to this circumstance, and cor- 



* Loc. cit. 



