184 KANSAS CITY REVIEW OF SCIENCE. 



aware of any observations made to determine this point. In Munich, where the 

 ground water flows toward the river Isar, which divides the city, it has been 

 found that the annual range or oscillation (the difference between the highest and 

 lowest level during the year) is ten feet, while the horizontal movement amounts 

 to fifteen feet per day. In Buda Pesth the annual range was found by Fodor to 

 be less than three feet, while in some portions of India it amounts to more than 

 forty feet. As it is from the ground water that the greater portion of the supply 

 of drinking water in the country and in villages and small towns is drawn, it 

 becomes at once manifest how important it is to prevent, as far as possible, pollu- 

 tion of this source. Cesspools and manure heaps and pits, of necessity, contam- 

 inate the soil, and also ground water, for a distance below and around them, and 

 such water is clearly unfit for drinking and other domestic purposes. Hence, 

 the reason why wells should not be placed too near privies and manure heaps or 

 pits becomes apparent. 



Between the level of the ground, or that portion of the soil where its pores 

 are entirely occupied by the water — where, in other words, the ground 'vs, saturated 

 — and the surface is a stratum of earth more or less moist; that is to say, the inter- 

 stices of the soil are partly filled with water and partly with air. It is in this stratum 

 that the processes of organic decay or putrefaction are going on, in consequence 

 of which the pollution of the ground air occurs. Recent observations seem to 

 show that these processes of decomposition are initiated and kept up by minute 

 organisms, termed bacteria, just as fermentation in liquids containing sugar can 

 only take place in the presence of the yeast plant. It has been found that v/hen 

 non-putrefactive decomposition goes on, there are always present multitudes of 

 one variety of these minute organisms ; while if putrefactive decomposition is 

 going on, a different variety of these organisms is present. Just as, when a fer- 

 menting liquid becomes putrid, the yeast plant disappears and its place is taken 

 by the ordinary bacteria of putrefaction, so in the soil, if the access of oxygen 

 which is necessary to the life of the bacteria of decay is prevented, these organisms 

 die and are succeeded by the organisms of putrefaction. It has been found that 

 in a soil saturated with water the bacteria of decay cannot live, while those of 

 putrefaction may flourish, because these latter organisms can sustain life in the 

 absence of oxygen. Prof. Fodor's researches indicate that the organism of non- 

 putrefactive decomposition or decay is that which is termed by Cohn bacterium 

 lineola ; and that the bacterium termo is the principal organism of putrefaction. 



IV. The Diseases Spread by Soil Impurities. — Given now an area of 

 soil, say the ground upon which a house or city is built, with a moist stratum in 

 which the processes of decay are active, and imagine a rise in the ground water. 

 The ground air, charged with carbonic acid and other products of decomposition, 

 is forced out of the pores of the soil by the rising ground water, and escapes into 

 the external air, or through cellars and basements into houses, and may there 

 produce disease. But the saturation of the soil with water prevents the further 

 development of the bacteria of decay, and putrefaction takes place. If, now, the 

 ground water sinks to its former level or below, the processes of the decay again 



