NOTES 129 



These disease-producing germs the bacteriologist 

 soon came to know very well as he grew them in the 

 safe purlieus of his laboratories and found out the 

 various ways in which they were able to work havoc 

 in the delicate mechanism of their earth-neighbor, 

 man. Thus the nature of disease became clearer and 

 the problems of its prevention and cure definite and 

 precise. 



BARRIERS OF THE BODY. 



The healthy human body is safe-guarded in many 

 effective ways against the entrance and continued life 

 of bacteria and allied organisms. The tough skin 

 affords a most impregnable barrier. The nose and 

 throat and the tubes leading to the lungs are protected 

 with various mechanisms barring the way to many 

 germs which dusty air bears in every breath. The 

 complex chemical processes in our digestive apparatus 

 which convert our food into building material for 

 brain and muscle spell death to the myriads of bac- 

 teria with which our uncooked foods are mingled. So, 

 altogether, our life among bacteria, even those of the 

 deadly sort, is usually exposed to little hazard. 



But when the best is said, these minute inciters of 

 disease do now and then win their way to the intimate 

 recesses of our bodies, producing serious results. The 

 measure of their ravages is found in the tables of the 

 statisticians, which show that a large proportion of 

 all who die fall victims to these invisible foes, and 

 that, too, at an age when life holds out its brightest 

 promise. 



