690 



APPENDIX. 



to examine the deposit in various fluids, such as water, mucilage, 

 spirit, Canada balsam, turpentine, &c. Occasionally it is neces- 

 sary to resort to certain chemical reagents, before the deposit can 

 be examined satisfactorily. Thus, in some amorphous sediments 

 containing lithic acid alone, or combined with alkaline bases, the 

 familiar rhomboidal crystals cannot be detected until the mass 

 be first dissolved with potash, and then treated with excess of 

 acetic acid. 



ORGANIC CONSTITUENTS OF URINARY DEPOSITS. 



In healthy urine the mucus settles towards the bottom, as a 

 flocculent, transparent, and somewhat bulky cloud. In this trans- 

 parent substance the microscope detects 

 FIG. 405. merely a few granular cells, larger than 



blood-corpuscles, of very delicate struc- 

 ture and surrounded by a few minute 

 granules. In disease the mucous de- 

 position often loses its transparency, 

 becoming viscid and thick from the 

 addition of various kinds of epithelium. 

 The peculiar appearance of the epithe- 

 lial cells will indicate the part of the 

 genito-urinary mucous membrane from 

 which the mucus was secreted. (Fig. 

 405.) In some diseases of the bladder, 

 as cystitis, a thick, glairy, and gela- 

 tinous deposit will often appear, simulating inspissated mucus. 

 This is pus chemically changed by contact with the carbonate ot 



ammonia generated in the de- 

 composition of urea by the al- 

 kaline mucus. Very minute 

 octohedral crystals of oxalate 

 of lime are sometimes found 

 like dark square-shaped specks 

 imbedded in the mucus. A 

 power of two hundred is gene- 

 rally sufficient to distinguish 

 them. Fragments of cotton- 

 fibre, hair, &c., are sometimes 

 found incrusted with these crys- 

 tals. 



The epithelium found in the 

 urine differs in different speci- 

 mens, according to the part of 

 the urinary apparatus from 

 which it is derived. In the con- 

 voluted portion of the tubuli 

 uriniferi it is glandular, and 

 forms a thick layer upon the basement membrane. (Fig. 406.) 



Mucous corpuscles and epithelium. 



FlG. 406. 



A, Portion of a secreting canal from cortical 

 portion. B, Epithelium gland cells, magnified 700 

 times, n, Portion of a canal from medullary sub- 

 stance of kidney. 



