60 BACTERIOLOGICAL DIAGNOSIS. 



ened, even although the upper part of the medium is 

 contaminated with other organisms. 



The only way in which the bacilli can be recognised 

 with absolute certainty is by means of animal experi- 

 ments, and to this end the practitioner should transmit 

 to the laboratory some of the scrapings from the deeper 

 portion of the wound in a test-tube sterilised by boiling, 

 or, still better, by dry heat. 



THE PNEUMOCOCCUS, PNEUMONIA, ETC. 



The pnemococcus is a very important organism, and 

 one which plays a prominent part in the production of 

 disease. It may occur in the mouth in a healthy 

 person ; hence its recognition in small quantities in 

 the sputum is not of diagnostic value. 



The pneumococcus is a very common cause of disease 

 of the respiratory system. It causes : 



1. Acute lobar pneumonia. Opinions differ as to whether 

 it is the only cause of this disease, though it appears 

 most probable that this is the case. 



2. Lobular (broncho-) pneumonia. This disease may 

 also be caused by streptococci, staphylococci, diphtheria 

 bacilli, influenza bacilli, plague bacilli, tubercle bacilli, 

 and others. The pneumococcus may also occur as a 

 secondary infection in lobular pneumonia due to any of 

 these. 



3. Pleunsy, either the serous, fibrinous, or purulent 

 varieties. It is important to notice that the prognosis 

 of empyema is better when the disease is due solely to 

 the pneumococcus than when other organisms (strep- 

 tococci, staphylococci, tubercle bacilli, &c.) are present, 



