270 BOARD OF AGRICULTURE. 



although practical experience teaches us that the danger 

 from this source is not very great. 



I have selected diphtheria to illustrate the dangers of con- 

 tagions simply because it is so common and well-known ; 

 but what I have said of it is true of scarlet fever, measles, 

 small-pox, whooping-cough, cholera, etc., so far as danger 

 of contagion is concerned, although there is a difference 

 in degree of the contagion of some of them ; for in- 

 stance, whooping-cough and measles appear to be carried 

 from one to another through the medium of the air much 

 more readily than some of the others. 



There is another broad highway from the sick to the well 

 through which contagious disease may travel, and one that 

 has the most important bearing on all sanitary work, — in fact 

 it is the chief corner-stone of sanitary science, — and that is 

 by means of filth and decomposing animal and vegetable 

 matter. We have repeatedly referred to the fact that these 

 little germs are transported from place to place through the 

 air. We have also learned that many of these disease-produc- 

 ing germs grow outside the body, that they require for their 

 growth a certain degree of warmth, moisture and some kind 

 of vegetable or animal matter. Now, suppose that near one 

 of your houses there is a pool of dirty, stagnant water in 

 which there is decomposing grass and other vegetable and 

 perhaps animal matter. Here are all the conditions for the 

 growth of some of these germs, and such a pool would 

 make an admirable garden for their cultivation ; or, suppose 

 a waste-pipe or spout from the sink is discharging its filthy 

 water directly on the ground at the side or back of the 

 house (and there are many such in the county districts 

 and small villages), and there creating a little pool, and 

 running from this there is a small stream extending perhaps 

 a number of rods. Such a pool and stream of dirty slop 

 water is another and a most excellent place for the growth 

 of these germs, the sowing of the seed being the only 

 necessity to ensure their development. And how readily 

 this may be done. For, suppose a neighbor a half mile or 

 more away has been unfortunate enough to have a case of 

 one of these contagious diseases in his house, and after re- 

 covery the housewife thinks it necessary to clean the room 



