254 THE AMERICAN MONTHLY [Noveinher, 



white, and while the value of such information is not fully determined, 

 yet it is generally conceded that the red globules are in excess where 

 the circulation is retarded, whereas their number is decreased in pro- 

 longed fevers, in cachectic conditions generallv, and after hemorrhages. 

 Their size, also, is subject to considerable variation, being increased in 

 chlorosis while in cancer it is dim.inished. The white corpuscles are 

 relatively increased in number after hemorrhages and in diseased pro- 

 cesses of the lymph glands. 



The parasites of the blood are not often sought for in general prac- 

 tice, but in certain cases the bacilli of anthrax, and of malaria, the 

 filaria sanguinis hominis, and the spirillum of relapsing fever may be 

 observed . 



Often it is only by the microscope revealing bone-cells in pus that it 

 is possible to decide whether an abscess is connected with bone or not. 

 Glycerine or a weak solution of potash will clear up the pus for such 

 examination. Epithelial cells from the kidneys or urinary passages 

 may indicate the source of pus from a sinus, or the connection of a fis- 

 tulous opening with the stomach or intestine ma}' be shown by the 

 character of the cells or by food mixed with pus. Echinococcus cysts 

 may be diagnosed from the presence of booklets, suckers, or other por- 

 tions of the parasite mixed with pus. 



Actinomycosis is detected by discovering portions of the fungus in 

 scrapings from the surface of a suspected growth. 



Diflei'ential diagnoses as to the nature of abscesses can also be made, 

 the micrococcus pyogenes tenuis indicating benign abscesses, and the 

 streptococcus pyogenes indicating slow inflammatory processes aflect- 

 ing the lymphatics, while in cases of rapid suppuration the staphylo- 

 coccus predominates. It has been hoped that microscopic examination 

 would detect a micro-organism peculiar to diphtheria, but so far the 

 appearance of croupous and diphtheritic patches is identical. 



From the examination of sputum assistance is obtained in the diag- 

 nosis of tuberculosis, catarrhal, or suppurative conditions of the lungs, 

 thrush (oidicum albicans), actinomycosis, and other diseases Hemor- 

 rhages of the stomach, cancer of this organ, and dyspepsia, also exhibit 

 their individual characteristics to the microscopist. 



In the fcEces we may find almost any animal or vegetable substance. 

 and it is only by a preponderance of one over others that much informa- 

 tion can be derived from this source. The presence of mucus in the 

 discharges suggests a diseased condition, but does not help in differen- 

 tiating unless it occurs with blood, as in dysenterv, or in casts of the 

 intestines, as in pseudo-membranous enteritis. Ova of the various 

 parasites inhabiting the intestines are frequently found in passages from 

 the bowels. 



In the substance of the muscles mav be found tlic trichiutE spirales. 

 while on the surface of the skin the microscope enables us to studv the 

 acarus scabiei or itch insect, showing that the itching is due to the young 

 parasites, often numbering as high as forty in a single burrow, as thev 

 follow the crevices in the skin, till finally they perforate it. Herpes 

 tonsurans is shown to be due to a fungus growth, as is also sycosis and 

 favus. 



But it is when we come to urinary examination that we approach the 

 most frequent use of the microscope in clinical medicine. The pres- 



