1889-90.] NATURAL HISTORY OF GROUND WATERS. 169 



the soil, it passes slowly by percolation downward and loses gradu- 

 ally through capillary attraction, lessened nutriment, decreased amounts 

 of oxygen and increased amounts of carbonic acid, its previous bac- 

 terial pollution, and with few exceptions appears in springs and sub- 

 terranean waters, where tapped either by tube or the common pit 

 wells, as absolutely sterile or wholly devoid of bacterial life. 



7. That in the tube wells, with careful driving of the iron tube to 

 prevent soakage along the outside, and a brief pumping to carry off 

 the contaminating bacteria which reach the inside through aerial con- 

 tamination, we can obtain a practically sterile water of first quality for 

 drinking purposes. 



8. Through organic soakage in the upper and most readily accessible 

 direction for the lateral movement of subsoil waters, such waters carry 

 abundant nutriment for bacteria, which are carried in the same manner 

 and by the filthy washings of the top and from the air which occupies the 

 pit, with little aeration and the absence of sunlight and a temperature in 

 shallow wells affected by external temperatures, conditions most favor- 

 able for the development of bacteria exist. Hence these wells under 

 ordinary circumstances, but especially where found in back yards, under 

 kitchens, in barnyards or as shallow dug outs in the black soils of the west 

 and all newly-settled countries, are veritable pest-holes, more dangerous 

 to the health than probably all other local sources combined in those 

 seasons when low temperatures do not prevent bacterial development. 

 They are really what Pflugge calls them, " hygienic monsters." 



I conclude this paper on a subject which is exhaustless, in the words 

 of Duclaux, " One suspects more a water which receives a minimum 

 quantity of excrementitious matters than a water which might be charged 

 with germs after the water had run over a desert region. This question 

 of the nature of germs is too important for us to dream of limiting it by 

 the length of this review already too long, in which we have wished to 

 study the question of quantity. But in waiting that one may find the 

 means of indicating in a water the hurtful or pathogenic germs which it 

 contains, and having found in this way a measure of the degree of 

 their nocuousness, we confess that the only waters to be recommended 

 are those which contain no germs at all," 



