" THE LEAVES OF THE TREE Were FOR THE HEALING OF THE NATIONS. ' 41 



11 The same French scientist found that in summer, whether in city or country 

 the air contains three or four times more germs than in winter ; that the air at 

 elevations is always less densely populated by them than that near the surface of 

 the earth, and that the air on sea or on mountain heights is almost entirely free 

 from them. It is generally to be regretted that this scientist did not extend his 

 investigations to the atmosphere of one of our Mission-street horse-cars, habitually 

 crowded with passengers and with every door and window tightly closed. The 

 man who does examine one of these tor germs will, no doubt, find " there's mil- 

 lions in it !" 



"The dwellers of the air vary greatly in size. Some appear under the microscope 

 as minute, rounded dots. These have been, therefore, the points of beginning for 

 all living things. From such an assumed origin comes every plant, every animal 

 and every human creature, by multiplication and differentiation, by growth and 

 development. The difference between a bacterium and a man is that the bacteri- 

 um never gets beyond the starting-point. It begins and ends its existence as a 

 single cell. Such as it is in structure all living creatures once were, and the mys- 

 tery of its origin and creation is as great as that of man. The humble coccus, 

 standing on the very threshold of that domain where living things abound, pre 

 sents a problem as profound as that of the genesis of a human soul. It possesses 

 life, and that possession in spite of its simple form makes the coccus an object of 

 absorbing interest and of deepest awe. 



"One of the most familiar manifestations ot the presence in air of unseen germs is 

 the formation of mold, such as is frequently seen on bread, fruit or cheese. To the 

 naked eye this is only an ugly scum or fuzz that can be easily scraped away from 

 the surface and causes no perceptible changes in the parts beneath. Under the 

 microscope this would become a luxuriant field of green as beautiful as tbe expanse 

 of waving grain that clothes the plains in spring-time. Air always contains these 

 mold germs, but they do not take root and grow on the surface where they chance 

 to light, else mold would be the rule instead of an occasional occurrence. These in- 

 finitisimal seeds must be well watered or they die. This we express when we say 

 that mold forms only in places that are moist or damp. The mold germ that thrives 

 on bread is not the one that finds nourishment in the juice of fruits, nor the one 

 that lives by preference in the barnyard. 



"Some years ago, during excavations in the buried city of Pompeii there were 

 found several jars of preserved figs, hermetically sealed, which had been prepared 

 by some good housewife of that ill-fated city, eighteen hundred years before When 

 these jars were opened the figs proved to be as fresh and delicious as if put away 

 only the summer previous. It is said that that discovery taught the present century 

 the art of preserving fruit. This art, so familiar to every household, depends mere- 

 ly on the exclusion of the germs of fermentation. There are other kinds of germs 

 whose importance is very great, for they find their residence, not in the dead, bir, 

 in living tissues, and thus become a menace to the health and even the life of man. 

 Does all air contain disease germs, and is there any way to prevent their presence 

 there ? These are questions of vital importance to the human race. Fortunate y 

 for man, such germs are not always hovering about him. Air is seldom entirely 

 free from microscopic forms of life, but the majority of such is perfectly harmless to 

 man (?) It is only exceptionally that air contains those varieties that cause disease. 

 There are two sources for their occurrence in the air of any particular locality: 



"First: They come from decomposing material; for while some disease germs will 

 not, so far as known, multiply outside of the body of infected animals or human 

 lungs, there are others that do multiply abundantly under favorable conditions as 

 to food and temperature. This is the case with germs of typhoid fever, diphtheria, 

 slanders, cholera and erysipelas. All of these thrive in filth of any sort. be 

 fecond source of disease germs in the air of a locality is the presence of cases of 

 disease. From a human bodv in which these parasites are living some are con 

 stantly escaping. Deprive disease germs of the inefficient sewers which are to them 

 as the promised land, flowing with milk and honey and build more > harbors ^ of 

 refuge, equipped with the means to put the enemy to route-then and not till then 

 will the city become a safe place for residence when epidemics threaten. (S. F. 

 Bulletin, February 25, 1893.) 



