664 APPENDIX. 



withstanding that Goodsir, Kolliker, and Johnson have described 

 and figured it. "With care," says Mr. Beale, "I believe it may 

 always be demonstrated in the healthy human kidney ; and in 

 some specimens of fatty kidney, as well as in the small con- 

 tracted kidney of chronic nephritis, it may very readily be seen 

 by washing a thin section with a stream of water, in order to 

 remove the epithelium and remaining portion of the tubes. The 

 matrix appears to consist of very fine fibres, amongst which no 

 indications of the yellow element can be detected. By the ad- 

 dition of acetic acid it becomes more transparent, and a few 

 granules are developed, but no other change is produced." 



In the uriniferous tubes of the frog and newt, ciliary motion 

 is beautifully shown. The arrangement of the vessels of the 

 Malpighian tufts can be studied with facility and success in the 

 large tufts of the kidney of the horse. 



Sections of kidney are best kept in large thin glass-cells con- 

 taining a solution of creasote or weak spirit and water. 



Morbid Kidney. In disease the kidney oftentimes becomes 

 quite opaque. This condition may result from a variety of 

 causes ; as, hypertrophy of the matrix, deposition of fatty matter, 

 and unusual accumulation of epithelium or oil-globules in the 

 tubes. To examine such a kidney, therefore, the sections should 

 be exceedingly thin. The matrix and the vessels, which are often 

 much thickened in chronic nephritis, should be prepared for 

 examination by the addition of acetic acid, or dilute caustic 

 soda, and subsequent washing with clear water to remove the 

 epithelium and granular matter from the tubes. 



Salivary Glands. To examine the structure of the salivary 

 glands, thin sections of the fresh gland should be treated first 

 with acetic acid, and then with caustic soda in excess. The 

 epithelium of the ultimate lobules is rendered distinct by soaking 

 the section in acetic acid. In the ducts, large cells filled with 

 oil-globules may sometimes be detected. 



Thymus and Thyroid G-lands. Sections of the recent glands 

 should, before being submitted to examination, be washed with 

 water to clean away the soft and pulpy portions, which are apt 

 to obscure the structure of the tissues. The relation of the lobules 

 and other constituents is best shown in sections hardened with 

 chromic acid ; though it must be borne in mind that this process 

 alters the natural appearance of the cellular tissue. The mem- 

 branous thyroid gland of small animals is well adapted for micro- 

 scopic examination. 



Adipose Tissue. To examine adipose tissue, small masses of 

 fat-cells may be taken from the subcutaneous areolar tissue, and 

 exposed to reflected light under a low power ; or thin sections, 

 moistened with water, may be placed between two pieces of glass, 

 and examined by means of transmitted light. The arrangement 

 of vessels can only be demonstrated upon an injected prepara- 

 tion. Small acicular crystals, of margaric acid and margarine, 



