22G ANNUAL OF SCIENTIFIC DISCOVERY. 



of Europe and America, evidence which, if not conclusive, is at least ex- 

 ceedingly interest in*;;. 



Thus, the injuriousncss of imperfect drainage is said to arise from the nox- 

 ious influence of all organic matters animal and vegetable when in a 

 state of decomposition. That putrid flesh and vegetables are generally 

 unpleasant, both to tnste and smell, is a fact; but are they as injurious as 

 they are unpleasant? Some putrescent matters are injurious when eaten, 

 alihough many can be, and are, eaten with impunity; and all of them are 

 injurious if they enter the blood. The surprising fact that the Indians kill 

 their game with poisoned arrows, yet suffer no harm from eating the flesh 

 thus poisoned, is intelligible to the physiologist, who sees that the poison of 

 the arrow enters the blood of the animal ; but the poison of the poisoned 

 flesh, which is eaten, does not enter the blood. It is on the same principle 

 that we can explain why an anatomist may spend day after day over putrid 

 bodies (in an atmosphere the stench of which makes a stranger sick), yet 

 suffer no harm beyond what would result from sedentary confinement in any 

 other room; nevertheless, let this anatomist scratch himself with the scalpel 

 which he has just used, and this little wound may be his death. He could 

 breathe the air laden with the products of decomposition, and, if oxygen 

 were sufficiently abundant for respiration, no harm Avould ensue; but he 

 could not admit decomposing matter into his blood without serious injury. 



In the above paragraph we have briefly stated what seems to us the physi- 

 ological principle involved in this question. Putrid substances are poison- 

 ous only in the blood; but the gaseous products of putrescence are not 

 poisonous. A stink is unpleasant, but it is not poisonous. "We assume, of 

 course, that the gaseous products are not too abundant to prevent respira- 

 tion, otherwise the effects of imperfect respiration will ensue; but these are 

 not cholera or fever. 



With this preliminary explanation, let ns now look at Dr. Parkin's evidences. 



Mnjendie arranged a cask in such a way that the bottom could hold putrid 

 substances, whilst animals were placed on a grating with a double bottom, 

 exposed to the emanations which constantly escaped. Rabbits, guinea-pigs, 

 and pigeons were left thus for a month, but did not experience any ill result. 

 Dogs, on the contrary, began to lose flesh on the fourth day, and, although 

 they preserved their gayety and appetite, died at the end of ten or fifteen 

 days. But the dogs showed none of the symptoms of poison ; they showed 

 none of the symptoms observed in dogs into whose veins putrid matters had 

 been injected. Their death was obviously caused by imperfect respiration. 

 Ilubbits and guinea-pigs require less oxygen in a given atmosphere than 

 dous. bv reason of their smaller size. But that exhalations from decaving 



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matters are not injurious when respiration is unimpeded, seems evident from 

 the experience of leather-dressers, knackers, butchers, and others. Mr. Xew- 

 man informs us that the leather-dressers in Bristol are not only healthy, but 

 more so than the rest of the neighboring poor, although, during the last part 

 of the process, the stench is almost intolerable. In the tan-yards at Ber- 

 mondscy there are about seven hundred workmen, all remarkably healthy. 

 Again, Dr. Chisholme says that, in a manufactory near Bitton, for the pro- 

 duction of muriate of ammonia and sulphate of soda, and where the distilla- 

 tion of the medullary oil produces the most nauseating fetor, no fever is 

 known to arise, although the neighborhood is thickly populated. The same 

 exemption has been remarked at a manufactory near Bristol for the conver- 

 sion of dead animals into a substance resembling spermaceti, and where the 



