HEALTH. 63 



oners died like dogs "because they were compelled to 

 inhale air poisoned by carbonic-acid gas and destitute of 

 oxygen"? But the cause thus given for this wholesale 

 slaug-hter is another of those world-wide mistakes that 

 modern science is revealing day by day. It has been 

 proven of late that these unfortunate men, shut up like 

 rats in a trap, without light or ventilation, died not from 

 too much carbonic-acid gas or too little oxygen, but from 

 the presence of organic matter in the air, diseased germs, 

 too minute to be visible, yet all powerful to sow the seeds 

 of malaria broadcast, and contaminate all with which they 

 came in contact. 



That country air is purer than city air is universally 

 conceded, but, as we have just observed, it is not the ab- 

 sence of gases to a greater degree in the former that gives 

 it the advantage. No, not in the gaseous, but in the solid 

 portions of the atmosphere do we find the mischief-maker 

 enthroned. 



" It has been established beyond all doubt," says Shroe- 

 der, ' ' that these organic substances, be they the gaseous 

 products of putrefactive processes in the animal or vegeta- 

 ble kingdom, floating in the atmosphere, do reach the lungs 

 in the currents of air inspired, and are there capable of 

 doing great mischief." 



So we see that it is these germs, or "seeds of disease," 

 as they have been appropriately termed, that cause the 

 trouble ajid contaminate the air, and these are found, as 

 would seem most natural, in much greater quantities in 

 the atmosphere of the cities than in that of the country. 

 In the one thousands of agencies are at work to produce 

 and encourage their presence ; in the other the leaves of 

 the trees, the grass, the growing crops, the sparkling river 

 or lakes, all serve to keep the air pure and sweet. But of 

 course these ' ' seeds of disease " do exist in some localities, 



