PNEUMONIA 209 



ceptible to infection because of a localised congestion 

 or inflammation of the mucous membrane, or a low- 

 ered vitality of the tissues due to some of the causes 

 previously mentioned (alcoholism, crowd-poisoning, 

 etc). My own researches and those of other investi- 

 gators show that this micrococcus is present in the 

 salivary secretions of a considerable proportion of 

 healthy persons, both in this country and in Europe. 

 Also, that it varies greatly in pathogenic virulence as 

 obtained from this source and from the sputa of pa- 

 tients with pneumonia. 



Epidemics of pneumonia, in prisons, and on ship- 

 board, have occurred with sufficient frequency to show 

 that the disease may be communicated by the sick to 

 those associated with them. That this does not occur 

 more frequently is probably due to the fact that pa- 

 tients with pneumonia are confined to bed and that 

 the abundant expectoration, among decent people, 

 could scarcely fail to be deposited in a receptacle of 

 some kind, or to be wiped from the mouths by hand- 

 kerchiefs or cloths which are destroyed by fire or sent 

 to the laundry. Also to the fact that the micrococcus 

 of pneumonia has far less resisting power to desicca- 

 tion than the tubercle bacillus or the diphtheria bacil- 

 lus and would be less likely to survive in dust. The 

 tenacious sticky nature of the sputa also prevents, to 

 a great extent, the coughing up of minute droplets, 



