318 Wisconsin State Hoeticultural Society. 



tions come from the air, while undergoing examination. If a 

 transparent liquid containing a small quantity of organic matter 

 is exposed to the air it becomes clouded in a short time, and the 

 microscope will show that it contains myriads of these bodies. 

 Their presence in the atmosphere has been ascsrtained by forcing 

 currents of air through tubes lined with sticky substances, or 

 closed at one end with wads of cotton. After the air has been 

 thus filtered the cotton is found to be filled with these germs. 

 Water may be filtered in the same way and the germs collected. 

 The following extract from an article in the London Nature, giv- 

 ing the results of experiments made in Paris, will give a better 

 idea as to the numbers found in air and water : " It will aston- 

 ish many persons, no doubt, to inform them that even the purest 

 country air is peopled with a host of microscopic corpuscles, 

 which enter into our lungs together with the air we breathe, and 

 which come in time to take up their residence in our own bodies, 

 as in a well-furnished house all prepared to receive them. The 

 surprise would be greater and even more disagreeable should we 

 add that the number of these germs, thus held by the air in sus- 

 pension, enormously increase in places thickly or even constantly 

 inhabited — that there is not a bedroom, a saloon, even an attic, 

 in which they do not swarm ; that in great cities they multiply 

 to fantastic proportions. The most densely inhabited parts of 

 the city are also the most populous with microbes. The air is 

 ten times thicker with germs in the heart of Paris than in the 

 neighborhood of the fortifications. The proportion also varies 

 according to seasons ; it is greatest in summer, lower in winter, 

 diminishes in autumn. There are variations likewise correspond- 

 ing to the state of dryness or dampness of the streets. The air 

 is most infected during the periods of summer, when, by reason 

 of the scarcity of water, the streets are not sprinkled, and the 

 dust flies everywhere. At such times not less than 5,000 bacte- 

 ria have been found to the cubic metre (39.33 inches) of air. But 

 while at Paris, even in the rainy season, one must always reckon 

 upon the germs in the interior of dwellings, and daily scat- 

 tered to the winds every time that rooms are cleaned ; in the 

 country, upon the other hand, once the atmosphere is well swept 



