§ 5. So far as observations have been made on the point (and the more those reported upon it are scrutinized, the less trustworthy they appear to be), workmen so exposed do not appear to be peculiarly subject to epidemics; many, indeed, appear to be exempted from them to such an extent as to raise a presumption that such emanations have on those “acclimated” to them an unexplained preservative effect analogous to vaccination. That one miasma may exclude, or neutralize, or modify the influence of another, would appear to be _primâ facie_ probable. But it is now becoming more extensively apparent that the same cause is productive of very different effects on different persons, and on the same persons at different times; as in the case mentioned by Dr. Arnott of the school badly drained at Clarendon Square, Somers’ Town, where every year, while the nuisance was at its height, and until it was removed by drainage, the malaria caused some remarkable form of disease; one year, extraordinary nervous affection, exhibiting rigid spasms, and then convulsions of the limbs, such as occur on taking various poisons into the stomach; another year, typhoid fever; in another, ophthalmia; in another, extraordinary constipation of the bowels, affecting similar numbers of the pupils. Such cases as the one before cited with respect to the depôt for animal matter in Paris, where the workmen suffered very little, whilst the people living near the depôt were “tormented with fevers,” are common. The effects of such miasma are manifested immediately on all surrounding human life (and there is evidence to believe they are manifest in their degree on animal life[4]), in proportion to the relative strength of the destructive agents and the relative strength or weakness of the beings exposed to them; the effects are seen first on infants; then on children in the order of their age and strength; then on females, or on the sickly, the aged, and feeble; last of all, on the robust workmen, and on them it appears on those parts of the body that have been previously weakened by excess or by illness. Whilst M. Parent Duchâtelet was looking for immediate appearances of acute disease on the robust workmen living amidst the decomposing animal effluvium of the Montfaucon, I have the authority of Dr. Henry Bennett for stating that he might have found that the influence of that effluvium was observable on the sick at half a mile distant. “When I was house surgeon at St. Louis,” says Dr. Bennett, “I several times remarked, that whenever the wind was from the direction of the Montfaucon, the wounds and sores under my care assumed a foul aspect. M. Jobert, the surgeon of the hospital, has told me that he has repeatedly seen hospital gangrene manifest itself in the wards apparently under the same influence. It is a fact known to all who are acquainted with St. Louis, that the above malady is more frequent at that hospital than at any other in Paris, although it is the most airy