NITRATE OF SILVER PREPARATIONS. 79 



nation, because, as may be made out by a careful compari- 

 son of specimens of connective tissue from the same part, 

 some prepared with logwood or chloride of gold, to show 

 the cells, others with silver, to show the cell-spaces, the 

 cell-spaces are in many cases distinctly larger than the 

 cells, and may also he of a somewhat different figure; 

 they are not necessarily, therefore, as has sometimes been 

 supposed, and as is no doubt the case with the clear parts 

 of a silvered epithelium, merely the cells left white. The 

 difference in the relative size of the cell-spaces and the 

 contained cells obtains no doubt more frequently, or at 

 least can be more readily made evident, in the firmer 

 varieties of connective tissue, where the ground substance 

 is everywhere pervaded with fibrous bundles, and has in 

 consequence lost its soft and yielding nature, which other- 

 wise permits it to adapt itself more readily to the shape 

 of the cells. Moreover it must be remembered that the 

 natural course of the lymph in the tissue is around the 

 cells, between them and the inclosing ground substance; 

 and when from any cause that fluid is in excess the effect 

 will be that the cell-spaces are more distended and appear 

 preternatu rally large. 



This much having been said in order to explain 

 the appearances produced by the silver method of 

 treatment appearances which have been called in 

 question, and their value as yielding evidence of any 

 constant structure in the tissues altogether denied 

 by histologists of considerable eminence, but, as it 

 must now be admitted, without sufficient grounds 

 the best mode of applying it to ordinary connective 

 tissue, such, for instance, as the subcutaneous, may 

 now be described. 



Preparation 7. The skin of a recently killed 

 rabbit or guinea-pig 1 having been stripped off one of 



1 These ammals are selected because there is likely to be less 

 fat in the subcutaneous tissue than in that of the cat or dog or 

 other animals commonly used in the laboratory. It is important 

 to remember that any tissue which is to be submitted to the silver 

 method must be fresh and unacted upon previously by any re- 

 agent whatever, since this would entirely prevent the desired 

 effect; moreover, if blood have accidentally got on to the part, it 

 must first be rinsed away by distilled water. 



