MOULDS. 147 



grounds for believing that the European centre was 

 Belgium : but if M. Boussm<mult was correct in 

 stating that " this malady is well known in rainy 

 years at Bogota, where the Indians live almost 

 entirely on potatoes/' then it is not of European 

 but American origin, and is probably derived from 

 districts not far remote from those whence Europe 

 first received the potato itself. 



It would occupy too much space to detail the 

 different theories and opinions relative to the causes 

 of this disease to which 1845 and subsequent years 

 gave birth. Suffice it to say, that the lapse of 

 years has silently proved the majority of these to 

 have been fallacious. All such as imputed to pecu- 

 liar electric conditions, a wet season, or other 

 meteorological influences, the disease which has 

 re-appeared under different conditions and in- 

 fluences, and in seasons remarkable for dryness, 

 are manifestly refuted ; whilst its mycological 

 origin has continned to gain adherents, and the 

 gradual accumulation of fresh facts has almost 

 placed it beyond dispute not only that the potato 

 disease is accompanied by, but results from, fungal 

 growth. Unfortunately, this disease has been so 

 prevalent, more or less, during the past thirty 

 years, that few have been without the opportunity 

 of making themselves acquainted with its external 

 appearance. To this may be added the minute 

 and exact account of its development, as recorded 

 by that excellent mycologist and careful observer, 



L 2 



