THE KIDNEYS. 231 



in a separated condition the cellular elements which 

 it contains, and of which it is composed, a small 

 portion of the fresh organ may be teased out with 

 needles in a little salt'solution or serum. But it 

 will be found that so much blood is incorporated 

 with the spleen substance (it forms, in fact, most of 

 the soft matter which can be expressed from the 

 fresh section) that the view of the other parts is 

 obscured by innumerable red blood corpuscles. 

 Hence before teasing a piece it should be placed for 

 forty-eight hours in J per cent, bichromate of potash 

 solution. This destroys the red corpuscles whilst 

 preserving the character of, and at the same time 

 macerating somewhat the proper substance of the 

 spleen, so "that the cells are now readily separated 

 and seen. By far the greater number are lymph 

 corpuscles from the lymphoid tissue of the Malpig- 

 hian nodules and of the arterial adventitia. But, 

 besides these, other cells are met with ; larger, often 

 flattened, and many of them with fine branchings. 

 These are cells of the retiform tissue ; some of them 

 contain pigment granules, as already intimated. 

 They may be found^either entirely isolated, or form- 

 ing a fine network by the intercommunication of 

 their branches. Their nuclei, as well as those of the 

 lymphoid cells, are well brought out if a little log- 

 wood solution is permitted to pass under the cover- 

 glass. In the fresh preparations, not treated by bi- 

 chromate of potash or any other reagent, but made 

 in serum, some of the cells may perhaps be found 

 containing red blood corpuscles in their interior, and 

 transitions from these to those containing pigment 

 are met with. 



THE KIDNEY. 



Preparation 5. The uninjected kidney. The 



kidney is hardened in the same way as the liver and 

 spleen, viz., by a strong solution of bichromate of 

 potash (two per cent.). The piece or pieces that are 



