246 peesident's address — section i. 



peculiarities or habits which will influence the individual susceptibility 

 or non-susceptibility towards aerial infection, and two of these may 

 be noted here. The person who habitually keeps his mouth open 

 must be more liable to this method of infection than the one who 

 filters the air through the nose. Again, a man who uses the handker- 

 chief freely will remove bacteria more frequently from the nasal 

 m.ucous membranes, and will retard the multiplication in the nasal 

 slime, and subsequent migration to the post - nasal cavities and 

 throat. 



The spread of infection by the air has been specially investigated 

 during the past few years in the case of the tuberculosis bacterium, 

 one of the most insidious of all the aerial bacteria, and the data that have 

 been collected with regard to this bacillus is largely applicable to all 

 the others. Tuberculosis may be contracted by way of the intestinal 

 or respiratory tracts. It appears to be by the former channel that the 

 child is generally attacked, and by the latter that the adult is infected. 

 The protection of the child may be easily accomplished by sterilising 

 its food and drink, ((^) but the sterilisation of the atmosphere is a practi- 

 cal impossibility. The most we can do to overcome this subtle form 

 of infection is to minimise, as much as we can, the pollution of the air. 

 A phthisical patient is not always dangerous ; it is only when bacterial 

 matter is coughed up into the air or into the mouth that the pollution 

 of the atmosphere becomes possible. Laschschenko (27) found tubercu- 

 losis bacteria in nine tests out of 20 in the saliva and spittle of patients. 

 But, as we cannot tell when the salivary spray is dangerous or when 

 it is not, it is necessary for purposes of prevention to assume that it 

 is always dangerous. Unfortunately the tuberculosis bacterium is 

 rather a resistant microbe, and is not so easily destroyed by exposure 

 to air and by drying as Bad. typhi or even Bac. diphtherice. When 

 in soil dust it persists in the light for from eight to 14 days, in dried 



(d) In this connection the views of the International Congress upon Tuber- 

 culosis, held in Paris, in October, 1905, may be noted. While recognising the 

 danger of transmission from man to man it also emphasized the possibility of the 

 transference of bovine tuberculosis to man, in spite of the views of Koch regarding 

 the dissimilarity of bacteria of human and bovine origin. In consideration of the 

 recent experimental evidence concerning the rather frequent occurrence of virulent 

 tubercle bacteria in the milk of tuberculous cows, and in consideration of the 

 possibility of infecting the intestinal tract with tuberculosis, which is more frequent 

 than has hitherto been supposed, the Congress decreed that the sanitary inspection 

 of all cow-byres should be performed as speedily as possible, and that in public 

 institutions of every kind — hospitals, schools, &c. — only pasteurised, sterilised, or 

 boiled milk ought to be admitted for use ; otherwise, milk should only be accepted 

 from those byres in which the animals had been tested with tuberculin and had 

 been found to be free from tuberculosis. 



This advice is excellent ; but, failing the compulsory testing of our herds, it 

 behoves us to insist upon all our milk being pasteurised lefore use. It is fortunate 

 that our climate practically compels the treatment, and that dm"ing the long, hot 

 summer months, both vendor and housekeeper find it to their advantage to pasteur- 

 ise in order to preserve the milk in a ch'inkable condition. Beyond the question of 

 keeping the milk sweet for a longer time, scientific pasteurisation aims at killing off» 

 or in destroying the viridence of, the more resistant Bac. tuberculosis at the lowest 

 temperature and in the shortest time, so that the taste, the solubility of the- 



