

ON DtsT AND DISEASE. 149 



that the matter which produces epidemic disease comes 

 always from a parent stock. It behaves as germinal 

 matter, and they do not hesitate to regard it as such. 

 They no more believe in the spontaneous generation of 

 such diseases, than they do in the spontaneous generation 

 of mice. Pasteur, for example, found that pebrine had 

 been known for an indefinite time as a disease among 

 silkworms. The development of it which he combated 

 was merely the expansion of an already existing powev 

 the bursting into open conflagration of a previously 

 smouldering fire. There is nothing surprising in this. 

 For though epidemic disease requires a special contagtum 

 to produce it, surrounding conditions must have a potent 

 influence on its development. Common seeds may be 

 duly sown, but the conditions of temperature and mois- 

 ture may be such as to restrict, or altogether prevent, 

 the subsequent growth. Looked at, therefore, from the 

 point of view of the germ theory, the exceptional energy 

 which epidemic disease from time to time exhibits, is in 

 harmony with the method of Nature. We sometimes 

 hear diphtheria spoken of as if it were a new disease of 

 the last twenty years ; but Mr. Simon tells me that 

 about three centuries ago tremendous epidemics of it 

 began to rage in Spain (where it was named Garrotillo], 

 and soon afterwards in Italy ; and that since that time 

 the disease has been well known to all successive gene- 

 rations of doctors. Jn or about 1758, for instance, Dr. 

 Starr, of Liskeard, in a communication to the Royal 

 Society, particularly described the disease, with all the 

 characters which have recently again become familiar, 

 but under the name of morbus strangulatorius, as 

 then severely epidemic in Cornwall. This fact is the 

 more interesting, as diphtheria, in its more modern 

 reappearance, again showed predilection for that remote 

 county. Many also believe that the Black Death, of 



