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 lobay 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. Lobulay (byoncho-) 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 imfection 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, 
