BOTRYTIS OF POTATO. 147 



diseased potatoes may be proved from the fol- 

 lowing singular circumstance : A quantity of 

 silk was, during the early part of the spring of 

 this year, (1846,) perceived to be greatly da- 

 maged by a white mould. On submitting a 

 portion of it, for examination, to an individual 

 eminent for a knowledge of fungi, it was at 

 once pronounced to be the botrytis infestanSt 

 or mould of the diseased potato. The mys- 

 tery was soon cleared up ; for the silk had 

 been dressed with starch from potatoes, and 

 proved a favourable situation for the develop- 

 ment of the fungus from the spawn that was 

 in it. Growth in such cases is extremely 

 rapid ; and when a potato plant is attacked by 

 the botrytis, of course the juices are consumed 

 by it, the elaboration of sap in the leaves can- 

 not go on, nor, from the stoppage of the sto- 

 mata by its threads, can admission of air, or 

 emission of any gas or fluid take place. It is 

 certain that the disease which destroyed such 

 quantities of the potatoes in America, Great 

 Britain, and over the continent of Europe, has 

 not yet been satisfactorily explained. Further 

 researches in plants more recently infected may 

 throw additional light on the important sub- 

 ject. Undoubtedly, in most instances the 



