i8 7 8.i 
to Health and Comfort. 
207 
mere feeling of discomfort — which, on the other hand, is 
particularly noticeable to the English visitor of our halls, 
who is apt to associate it with a supposed excess of heat. 
But this organic matter of exhalation is still one step re- 
moved from malaria ; it is only the ground of malaria — the 
soil on which a malarial growth .will propagate ; its decom- 
position is held to supply the means of fecundity to the germs 
of disease. In the warm air confined in the upper parts of 
rooms, with excess of moisture, it may undergo a rapid and 
somewhat foetid decomposition ; under such circumstances 
it is found to become offensive in six to ten minutes. With 
a smaller proportion of moisture, or when it is rapidly ab- 
sorbed with the moisture by diffusion into air of American 
dryness, it does not decompose so rapidly, but is likely to be 
absorbed by any hygroscopic substance the air containing it 
may come in contact with. The walls of rooms — especially 
the porous plastering, stone, o*r bricks, and possibly the 
papered and painted walls — will take up the excess of 
moisture with its organisms, and give up at another time, 
wholly or in part, the moisture without them. There is a 
characteristic smell of walls of kitchens, cabinets, hospitals, 
jails, court-rooms, and similar permanently occupied places, 
which can be developed in intensity by simply holding the 
half-closed warm hand against the face of the wall, and 
testing the result by the sense of smell of the hand. In 
such instances of retention of the results of imperfect 
ventilation, the eventual propagation of disease is a certain 
one. 
To the vegetable and lower animal growth the presence 
of moisture in the air seems a positive necessity ; where it 
is absent the}' perish, or at least no longer grow or propa- 
gate. The drinking animal apparently suffers the least of 
injury and but little discomfort in the dryness of the air, of 
whatever temperature. The immunity from disease to the 
human race which accompanies the drier regions of the 
earth has been frequently remarked, and the fadt meets 
general assent. The discomfort of the colder countries, 
even to the limits of the arCtic regions, is one of cold, not 
of absence of moisture. The assertion of relative insensi- 
bility to cold air devoid of moisture is the common report of 
all travellers in such regions, while the dreaded malarial 
diseases of more genial lands do not exist in them at all. 
In the temperate zone, in countries or localities which 
possess the driest of atmospheres, with the least variation 
of hygrometric condition, mankind is most free from disease 
of all descriptions. The elevated dry and barren lands of 
