298 FRAGMENTS OF SCIENCE. 



appearance, again showed predilection for that remote 

 county. Many also believe that the black death of five 

 centuries ago.has disappeared as mysteriously as it came, 

 but Mr. Simon finds that it is believed to be prevalent at 

 this hour in some of the northwestern parts of India. 



Let me here state an item of my own experience. When 

 I was at the Bel Alp last year the clergyman appointed to 

 that station received letters informing him of the breaking 

 out of scarlet fever among his children. He lived, if I re- 

 member rightly, on the healthful eminence of Dartmoor, 

 and it was difficult to imagine how scarlet fever could have 

 been wafted to the place. A drain ran close to his house, 

 and on it his suspicions were manifestly fixed. Some of 

 our medical writers would fortify him in this notion, while 

 those of another school would deny to a drain, however 

 foul, the power of producing a specific disease. After close 

 inquiry, he recollected that a hobby-horse had been used 

 both by his boy and another that a short time previously 

 had passed through scarlet fever. Drains and cesspools 

 are by no means in such evil odor as they used to be. A 

 fetid Thames and a low death-rate occur from time to time 

 together in London. For, if the special matter or germs of 

 epidemic disorder be not present, a corrupt atmosphere, 

 however obnoxious otherwise, will not produce the disorder. 

 Corrupted air may promote an epidemic, but cannot origi- 

 nate it. On the other hand, through the transport of the 

 special germ or virus, disease may develop itself in regions 

 where the drainage is good and the atmosphere pure. 



If you see a new thistle growing in your field you feel 

 sure that its seed has been wafted thither. Just as sure 

 does it seem that the contagious matter of scarlatina, or 

 any other contagious fever, has been transplanted to the 

 place where it newly appears. With a clearness and con- 

 clusiveness not to be surpassed Dr. William Budd has 

 traced such diseases from place to place; showing how 



