THE SPUTUM 113 



frequently extracellular, but some bacilli are frequently seen within 

 the cells. Gram's stain is not retained. It grows readily on blood- 

 serum, which is rapidly liquefied. 



Of the rarer causes of conjunctivitis, the staphylococcus, strepto- 

 coccus, and pneumobacillus may be mentioned. The latter may 

 be recognised by the presence of a capsule surrounding a bacillus 

 which greatly resembles an elongated pneumococcus, which does 

 not retain Gram (Plate III., Fig. 3). 



Diphtheria affects the conjunctiva, and its clinical recognition is 

 not usually difficult. But the bacteriological diagnosis (without 

 the use of animal inoculations) is complicated by the fact that 

 an organism — the xerosis bacillus — which closely resembles the 

 diphtheria bacillus may occur in the conjunctiva either in health 

 or in disease. It does not appear that the two can be differen- 

 tiated with certainty by morphological appearances, staining 

 reactions (the xerosis bacillus often shows polar granules), or 

 even by cultural tests. 



In tuberculosis 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 examination 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. 



8 



