646 IOWA DEPARTMENT OF AGRICULTURE. 



We find the crowded, poorly ventilated and dimly lighted rooms of the 

 tenement buildings are hot-beds of sickness, while other buildings in the 

 same localities into which the sunlight and fresh air had free access, 

 are peopled with robust men, women and children. If this imperfect 

 picture of the benefits of applied sanitation concerning the health of the 

 human race is a true history, even though no other evidence could be pro- 

 duced, I believe I would be justified in declaring to you today that these 

 same principles applied on your own farms and inside and all around your 

 stables and pens, would bring about a ruggedness of constitution in all 

 your domesticated animals that would greatly lessen their susceptibility 

 to infection and disease. 



The three great natural agents of sanitation are: pure air, sunlight, and 

 drainage. Many pathologic germs can not live if exposed to the influence 

 of the sun's rays, and all are deprived of the power of multiplication. 

 Moreover, light imparts increased vitality to both animal life and the 

 higher forms of vegetation, so that a double benefit is the reward of a 

 close friendship with the sunlight. First, the vitality of the germ life is 

 diminished, rendering unavoidable association with them less dangerous 

 to the animal. Second, the vitality of the animal life is increased, and a 

 consequent decreased vulner ability to contagion ensues. In other words, 

 our common enemy, the microbe, becomes weakened and less powerful in 

 its assault, while our fortifications are strengthened and better able to 

 resist their attacks. In the vegetable world a good lesson can be learned 

 of the benefits derived from air and sunshine, by comparing the apple 

 grown on the tree that has been intelligently pruned, with the unpruned 

 tree. On the former the fruit is large and a good color, texture and flavor, 

 and has good keeping qualities. The latter, being shadowed and deprived 

 of air to a certain extent by the dense foliage, is dwarfed and sallow, 

 watery in composition and an early rotter. I do not mean to assume that 

 there are no other advantages than additional air and sunshine to be 

 gained by pruning, but I do claim that these are of great importance. 

 Turn a trough upside down on the meadow and bore a number of holes 

 through it so that some air and just a little light is admitted, and you 

 will find that the grass thus Imprisoned will still grow, but note its 

 character. In a few days it becomes pale, soft and emaciated and as it 

 grows longer, it is noticed that every blade is attracted toward the out- 

 side holes, which soon become filled, and as the free ends protrude from 

 the openings they at once begin to take on more of the green, healthy 

 appearance of the surrounding grass. The principal cause which con- 

 tributes to this phenomenon is that darkness hinders the development of 

 the organic coloring matter or chlorophyll, which has the function of con- 

 veying oxygen to the plant tissues, and through the lack of this important 

 element, the vitality of the plant is weakened, and if these conditions are 

 continued long enough, its life is completely destroyed. The organic 

 coloring matter in the blood of man and of the lower animals is called 

 haemoglobin, and its duty like that of the chlorophyll of plants, is to 

 carry oxygen to the tissues of the body. Its development is also arrested 

 by darkness and in case of its deficiency, the body tissues are not properly 

 aerated and a consequent weakening of the animal constitution is the re- 

 sult. Darkness and imperfect ventilation are conditions that are usually 



