BAD AIR AND BAD HEALTH. 821 



breaks down the great mass of waste into harmless products, 

 there should be this comparatively slight residue left over — re- 

 minding one of a lawless fraction of people in an orderly state — 

 which can not be got rid of on the same easy terms. As we have 

 seen, we have about five pounds three ounces of daily waste that 

 is safely got rid of as urea, carbonic acid, and water, by means of 

 kidneys, skin, and lungs ; but accompanying this safe discharge 

 we have a few grains of poison — a sort of surplus of evil — which 

 in some way or other seems to resist the oxidation to which all the 

 other mass of waste has been subject. What, then, is this poison? 

 How far is it the same, how far does it differ from the normal 

 poisons of the tissues, which, as we see, in a few minutes destroy 

 life when oxygen is withheld? Where and how is it formed ? 

 Are we to look upon it as a putrefactive poison formed at the sur- 

 face of the lungs and the skin, when waste of some kind is escap- 

 ing through these channels ? Dr. Klein tells us (pages 61 and 241) 

 that septic bacteria* (the authors of putrefactive change) are to 

 be found in those parts of the body into which air penetrates, as 

 the mouth, the air-passages, the whole alimentary tract; but it 

 seems diflBcult not to believe, whatever changes take place as these 

 poisons reach the air, that they must at all events have existed as 

 chemical poisons when still in the tissues. Are we, then, to look 

 upon these poisons as derived from putrefactive decompositions 

 taking place in certain parts of the body ; or as poisons derived 

 from the tissues ; or as in turn possessing both characters ? At 

 present, both within and without the body, their nature is sur- 

 rounded with mystery, and many are the interesting questions 

 that remain to be solved about them. When they have passed out- 

 side the body, are they the food of any of the bacteria which are 

 found so plentifully in foul air? f If so, are the ordinary bacteria 

 (excluding the case of certain bacteria producing disease) our 

 friends or our enemies ; do they render the poison itself harmless ; 

 or do they themselves produce an excretion which is of a poison- 

 ous character ; or should they be looked on as neutral, destroying 

 one poison and producing another; are the poisons themselves 

 simply removed by currents of air, or are they oxidized in the 

 air ; if so, are they oxidized only when ozone is present (see Our 

 Homes, page 11) ; and if in the air, why not in the blood, after we 

 have rebreathed them and surrounded them with oxygen, in loose 

 combination with haemoglobin ? J 



* For a different view, see De Bary on Bacteria, p. 44. 



f Bicteria (Gr. hakterion, a staff) are the smallest livin,<T ora;anisins known, and gener- 

 ally included in the vegetable kingdom. They possess a very simple structure, are capable 

 of free movement, and multiply very rapidly. Some kinds are the causes of putrefaction 

 and of certain diseases. It is calculated that we inhale 300,000 germs of these organisms 

 in the day. 



X Mr. Wager adds the following note : " The bacteria on the surface are constantly at 



