THE SPLEEN. 229 



CHAPTER XVII. 



THE SPLEEN AND URINARY ORGANS. 

 THE SPLEEN. 



Preparation 1. The uninjected spleen. The 



spleen is hardened in the same manner as the liver, 

 by placing small pieces of it in 2 per cent, solution 

 of bichromate of potash, and in about a week or ten 

 days transferring them first to weak and then to 

 strong spirit. The sections, which cannot be too 

 thin, are to be stained deeply with logwood, and 

 mounted by the ordinary mode of precedure in 

 dammar varnish. 



In these preparations the Malpighian corpuscles' 

 (or nodules of lymphoid tissue) are very strongly 

 colored, as are also the trabeculse which traverse the 

 pulp, especially in those animals in which they are 

 largely composed of plain muscular tissue ; the sub- 

 stance of the pulp is but slightly colored by the log- 

 wood, only the cell-nuclei, and, to a much less extent, 

 the branching cells of the retiform tissue being 

 stained. The prevailing color of the pulp is yellow- 

 ish, owing to the blood (altered in color by the action 

 of the reagent) which at the time of death remained 

 in the interstices of the tissue. Moreover, here 

 and there a speck of coarsely-granular reddish-yellow 

 pigment may be detected, lodged in one of the cor- 

 puscles of the spleen pulp. But this will be better 

 made out in the teased-out preparations subsequently 

 to be described. 



Preparation 2. Irrigated spleen. By another 

 mode of preparing the spleen all the blood is first washed 

 out by a stream of salt solution, injected through the 

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