792 



SPLEEN. 



work of the pulp, I have not been able to find 

 out ; and I do not believe that either injec- 

 tion or inflation of the vein, or a microscopic 

 examination, will ever give any definite con- 

 clusion hereto. For these vessels, often pos- 

 sessing but a few little trabeculae for their 

 coats, are of such a delicate texture, that they 

 tear by the slightest mechanical force, while by 

 the microscope they cannot be distinguished 

 from the surrounding constituents of the pulp. 

 Yet thus much one may see, that the veins 

 gradually become very small, so small, that it 

 is quite impossible to talk of their commen- 

 cing as dilated spaces. For my own part, I 

 am convinced that a similar communication 

 obtains between the veins and capillaries of 

 oxen as of men ; and that the only possible 

 difference is, that the veins here possess only 

 an epithelium, and must therefore be con- 

 nected with the capillaries in a somewhat dif- 

 ferent way. I will yet further add, that in 

 microscopic examination of the pulp of ani- 

 mals, skeins of epithelium are not unfre- 

 quently found, consisting of roundish cells, as 

 it were, fused together : these can only come 

 from the small venous trunks. 



The following may be noticed concerning the 

 microscropic structure of the splenic vessels : 

 The arteries everywhere possess their three 

 usual coats. The inner consists, first, of an 



Fig. 535. 



Epithelial cells from the human Splenic artery, 

 a, shorter cells ; b, somewhat longer cells. 



epithelium of spindle-shaped cells, which 

 easily come off in skeins or separately (Jig. 

 535,a,6); and, secondly, of an elastic mem- 

 brane of homogeneous composition, wrinkled 

 in the longitudinal direction (Jig. 528, e.), and 

 with or without openings : which openings 

 although very small, are visible even in the 

 arteries of the tufts. The middle tunic is 

 very thick, and gives rise to the considerable 

 thickness of the wall of the vessel ; it con- 

 tains very little else but nnstriped muscular 

 fibres. In the larger and largest arteries, 

 nets of elastic fibre and elastic membrane 

 (gefenstiiie membranen of Henle) are also 

 present, while they exist without exception 

 on the vessels which pass to the Malpighian 

 corpuscles, and on those which form the 

 pencils or tufts. The adventitious for cellu- 

 lar) coat is altogether absent from the smaller 

 vessels in the interior of the j-pleen, and is 

 here represented by the sheath ; but it exists 

 in the larger vessels, and presents white 

 fibrous tissue and meshes of elastic fibres. 



The capillaries (fig. 536.) have'a simple, struc- 

 tureless membrane, with nuclei lying on its 



Fig. 53G. 



Capillary from the Spleen of the Pig. Magnified 350 

 diameters. 



inner surface. The veins have been already 

 described as they exist in brute mammalia : in 

 man they possess 1. An epithelium as above 

 described ; 2. A membrane of elastic longi- 

 tudinal fibres ; 3. Transverse unstriped mus- 

 cular fibres, in a single or double layer, which 

 are present in the trunk of the splenic vein 

 and all its primary branches in the interior of 

 the spleen, but are absent from the smaller 

 and smallest veins ; 4. White fibrous tissue, 

 with elastic fibres which take a longitudinal 

 direction. The smallest veins possess only 

 white fibrous tissue with elastic fibres, and 

 an epithelium. 



So much has been already said above con- 

 cerning the blood of the spfenic vessels and of 

 the spleen, that I will here only append some 

 special observations made upon animals. In 

 a dog whose spleen abounded in the dissolv- 

 ing blood globules, the blood of the splenic 

 vein distinguished itself by a very great quan- 

 tity of colourless blood corpuscles, almost all 

 of which contained numerous nuclei, and 

 often had a deceptive resemblance to pus 

 globules. In the blood of the liver were found 

 a great number of altogether different blood 



Fig. 537. 



(Oft 



Blood corpuscles from the liver and Splenic vein of a 

 Dog, with yellow crystals of a substance resembling 

 H&matine. 



globules'C/g. 537.). These were swollen out 

 and almost colorless, but contained from 

 1 to 5 thinner or thicker small rods of a dark 

 yellow colour ; part of these possessed the 

 same length as the blood globules, part were 

 shorter. These small rods were unchanged 

 in water, but in acetic acid they seemed to 

 disappear. In a second dog I found the 

 same cells with small yellow rods in the 

 blood of the splenic vein, while they could 

 not be detected in any other part of the body. 

 With them I found at the same time numer- 

 ous colourless blood globules with manifold 

 nuclei. In the fresh-water perch, the blood 



