WATER, SLOP AND SWUA. 4OO 



commenting upon this, says : "The hfe cycle of the para- 

 sites that affect animals, nearly always includes a stage 

 of development outside of the body. Moisture is a 

 necessary factor in their existence outside of the body 

 and hence it is that they are found in large number in 

 surface water, and are ingested (taken- up) with it. Bac- 

 teria can stand drying better than parasites, but must 

 have water in which to multiply. It follows, then, that 

 fewer parasitic diseases of stock will occur upon high 

 pasture land when well water is furnished than upon 

 bottom land where they must depend upon a supply from 

 otiier sources. Such parasitic diseases as worms in hogs 

 are largely due to surface water. 



"Whether water will act as an agent for the carrying 

 of the germs of disease, the ova, larv?e and special stages 

 of parasites, will depend upon the sources from which 

 the water is obtained. If it comes from a deep well 

 that is properly protected, these organisms will not be 

 present. If it is obtained from the surface, as small 

 ponds, ditches and streams, they may be present. Not 

 all surface waters are dangerous, but all are more or 

 less exposed to infection and may become dangerous at 

 any time. The time it becomes dangerous cannot he. 

 detected by the eye and may not be detected by laboratory 

 tests. 



1* "The earth acts as a filter for all germs that fall 

 upon it, no matter what may be their character. Only 

 a small per cent will pass through the first inch of soil, 

 and a very small number will pass through the first lo 

 feet. In the first few feet of soil most disease germs are 

 destroyed by other forms of life that inhabit it, but should 



