52 VETEEINAEY HYGIENE 



In obstetric cases the value of pure air is undoubted, but 

 both in this and the diseases mentioned above, it is impos- 

 sible to separate impure air from unclean surroundings, or 

 to accurately attach to each their respective share in the 

 production of trouble ; it is evident if the surroundings are 

 filthy the air must be impure. 



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