Miscellaneous Intelligence. 157 



and it is probable that the greater liability to these diseases of 

 persons living in crowded and unventilated rooms, is, to a large 

 extent, due to the special liability of such rooms to become 

 infected with the germs of these diseases. It is, however, by no 

 means demonstrated as yet, that the only deleterious effect which 

 the air of crowded barracks or tenement-house rooms, or of foul 

 •courts and narrow streets, exerts upon the persons who breathe 

 it, is due to the greater number of pathogenic micro-organisms in 

 such localities. It is quite possible that such impure atmospheres 

 may affect the vitality and the bacterioidal powers of the cells 

 and fluids of the upper air-passages with which they come in con- 

 tact, and may thus predispose to infections, the potential causes 

 of which are almost everywhere present, and especially in the 

 upper air-passages and in the alimentary canal of even the health- 

 iest persons, but of this we have as yet no scientific evidence. It 

 is very desirable that researches should be made on this point. 



X. The discomfort produced by crowded, ill-ventilated rooms 

 in persons not accustomed to them, is not due to the excess of 

 earbonic acid, nor to bacteria, nor, in most cases, to dusts of any 

 kind. The two great causes of such discomfort, though not the 

 only ones, are excessive temperature and unpleasant odors. Such 

 rooms as those referred to are generally overheated, the bodies of 

 the occupants and, at night, the usual means of illumination 

 contributing to this" result. 



The cause of the unpleasant, musty odor which is perceptible 

 to most persons on passing from the outer air into a crowded, 

 unventilated room is unknown ; it may, in part, be due to volatile 

 products of decomposition contained in the expired air of persons 

 having decayed teeth, foul mouths, or certain disorders of the 

 digestive apparatus, and it is due, in part, to volatile fatty acids 

 given off with, or produced from, the excretions of the skin, and 

 from clothing soiled with such excretions. It may produce 

 nausea and other disagreeable sensations in specially susceptible 

 persons, but most men soon become accustomed to it, and cease 

 to notice it, as they will do with regard to the odor of a smoking- 

 car, or of a soap factory, after they have been for some time in 

 the place. The direct and indirect effects of odors of various 

 kinds upon the comfort, and perhaps also upon the health of men, 

 are more considerable than would be indicated by any tests now 

 known for determining the nature and quantity of the matters 

 which give rise to them. The remarks of Renk (38, p. 174) upon 

 this point merit consideration. Cases of fainting in crowded 

 rooms usually occur in women, and are connected with defective 

 respiratory action due to tight lacing or other causes. 



Other causes of discomfort in rooms heated by furnaces or by 

 steam are excessive dryness of the air, and the presence of small 

 quantities of carbonic oxide, of illuminating gas, or of arsenic 

 derived from the coal used for heating. 



XL The results of this investigation, taken in connection with 

 the results of other recent researches summarized in this report, 



