the survival of the fittest. The managers of our railways are careful 

 whom they employ and still more careful whom they advance. A con- 

 ductor reaches his position by successive advancements, or the man best 

 suited to the position gets the place. A consumptive conductor or one 

 with a red, inflamed nose or watery eyes, or subject to chronic hoarse- 

 ness, is almost an anomaly on our large railways— if such a man did not 

 resign of his own accord because of his inal)ility to adapt himself to the 

 conditions, it certainly would not take long until the management "tired" 

 him. 



This weeding out process plays a most important part throughout life. 

 The most susceptible perish early; long lived individuals are found mainly 

 in thinly settled regions. It is often said of the backwood mountaineers 

 of some of our Southern States that they do not die; they simply wither 

 up of old age. 



It is not to be understood that everybody is susceptible to dust infec- 

 tions; as in all other diseases, there are always some persons who escape, 

 or who are attacked so slightly at the time of the prevalence of an 

 epidemic that we can scarcely consider them affected. On the other hand, 

 some individuals complain severely after each exposure, after a railway 

 journey, or after the pi'evalence of a windstorm or after attending a 

 crowded hall with poor ventilation, in fact any place where the atmos- 

 phere is contaminated. The cold may show itself the same day or not for 

 several weeks, as in the case of pleurisy. With many persons about who 

 are infected, the chance of becoming infected is of course greater. 



The habit of sweeping and dusting a closed room while persons are 

 compelled to be iu it is a most reprehensible one — the dust stirred into the 

 air irritates the respiratory mucous membranes, to say the least, and the 

 feather duster is a fruitful source of coughs and colds; it is too often 

 brought into action to dust the seats and furniture in a room or hall just 

 prior to the arrival of an audience.* The accumulated dust of a week or 

 more may be suspended in the air ready for inhalation, and we think little 

 about it, although a thick layer of dust on a chair we are about to occupy 

 strongly attracts our attention, and yet it is infinitely worse to inhale the 

 dust than it is to get it on our clothing. It is evident that this stirred iip 



°"NoTR. — To my certain knowledge this very thing occurred in the room where the Acad- 

 emy met ; dust which lay thickly on the chairs was stirred up with a feather duster half an 

 hour before we met. The amount of coughing and sneezing at the time this paper was 

 read was so noticeable that the newspapers called attention to it. 



