86 VETERINARY HYGIENE 



ORGANIC AND SUSPENDED MATTER. A considerable amount of 

 organic and participate matter is found in the air of animal quarters. 

 It originates from pulmonary exhalations, from cuticular debris, 

 from dust and pollen of foods, from desiccated faeces and from dust 

 and dirt brought in from the outside. Micro-organisms, too, are 

 found in varying quantities; these may or may not be of hygienic 

 importance. In cow byres they may be in sufficient numbers as to 

 cause serious pollution of the milk as it is gathered to the cans, and 

 they may be pathogenic to the animals. 



At one time it was thought that the organic matter was respons- 

 ible for the baneful effects caused by animal-life vitiation, and 

 attempts were made to show that expired air contains a specific 

 poison. It seems to be definitely settled now that " organic matter," 

 per se, is of but minor importance. 



The atmosphere in a badly ventilated room inhabited by people 

 has a peculiar and very disagreeable odour which is derived from 

 the organic matter given off from the body. Dr. de Chaumont 

 considered that the smell of vitiated air could serve as a fairly 

 reliable index of the degree of pollution, and he compiled a ta,ble 

 for the purpose of estimating by the sense of smell the amount of 

 CO 2 in the air. This table is given on page 107. 



Whatever value this test may have with regard to human habita- 

 tions, it is certainly of very doubtful utility in animal buildings. 

 In cow byres the air may contain a comparatively high proportion 

 of CO 2 and yet smell fresh, provided that the drainage is good and 

 the place kept clean. 



Mackenzie and Russel* from their investigations in the air pol- 

 lution of poultry houses concluded that " the smell of a house is 

 no guide to the purity of its atmosphere, but is due rather to the 

 droppings : a house may smell fairly sweet and yet contain an 

 excessive amount of carbonic acid." 



Each species of animal has an odour peculiar to itself which is 

 imparted to the surrounding atmosphere. Apart from the faecal 

 stench of foul pig-styes, no air contaminated by animals can smell 

 so foul as that of an over-crowded, unventilated room inhabited by 

 uncleanly persons. 



THE BAD EFFECTS OF IMPURE AIR. The result of keeping 

 animals or people in an impure atmosphere is not always obvious at 

 first. A badly ventilated animal house is an insidious danger. The 

 bad effects that follow the confinement of animals in a foul atmos- 

 phere are the result of an accumulation of forces. At some time, 

 possibly remote, there becomes evident a lowered vitality, a feeble 



* Trans. High, and Agric. Soc., 1908. 



