132 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



In tubemilosis of the conjunctiva it is usually necessary to excise 

 a piece of the lesion, and cut sections, but bacilli have been 

 detected occasionally in scrapings. 



THE SPUTUM 



The chief applications of bacteriology to the exannination of the 

 sputum have been mentioned already, but it seems advisable to 

 add a few general words on the subject. 



The selection of the material is of prime importance, since it 

 is obviously useless to expect an examination of the secretion 

 of the mouth and fauces to yield information as to the state of 

 the lungs. Where the sputum is copious the danger of this error 

 is not great ; in advanced phthisis the contents of a sputum-cup 

 taken at random will usually show signs of tubercle bacilli. Where 

 the sputum is but scanty the possibility is great, and in this case 

 the patient should be supplied with a clean (and, if possible, sterile) 

 sputum-cup, to be used only for collecting the material for examina- 

 tion, and he must be instructed to use it only after a paroxysm 

 of coughing, and when he distinctly feels the sputum come up from 

 the chest. If the patient is not sufficiently intelligent, the task of 

 collecting the sputum may be entrusted to a nurse, to whom the 

 importance of securing material directly from the lungs has been 

 explained. 



Where it is necessary to work with material which has been 

 collected without any precaution, the microscopical nature of 

 the cells may afford a clue as to its origin. Mucus or muco-pus 

 derived from the mouth, pharynx, etc., is characterized by containing 

 squamous cells ; these are of large size, flattened, have a compara- 

 tively small nucleus, and are often collected into groups of three 

 or four, with a distinct tessellated arrangement. They contain 

 granules (of keratin or an allied substance) which stain deeply by 

 Gram's method; they are also the last substances (other than 

 acid-fast bacilli) to be decolorized by the acid in the Ziehl-Neelsen 

 process, and when the decolorization has not been carried out 

 quite completely, may remain stained in the form of pinkish 

 plaques. The sputum which comes from the bronchi may be 

 characterized by the presence of columnar cells, which are occa- 

 sionally found to be ciliated, but in most cases this sign fails and 

 the sputum consists of mucus enclosing polynuclear leucocytes 

 and no characteristic cells of any kind. The same is true of the 



