310 Extracts from the Journals. [Oct., 



which it contains, and which has heen produced from the starch 

 of the barley, it is obvious that the same flavor may be imparted 

 by the addition of an equivalent amount of molasses or sugar, 

 should it be considered expedient." — London Gardeners'' Chron. 



THE POTATO DISEASE. 



BY JAMES CAIRD. 



As all the facts bearing upon the cause of the potato disease 

 are interesting at the present moment, I send one or two which I 

 think have not been previously observed A plot of early potatoes 

 were cut over some weeks ago, before the disease had anywhere 

 in this district I'eappeared, and while the shaws were perfectly 

 green and healthy. At that time the tubers were quite sound, 

 and continued so till a few days ago, when suddenly many of them 

 became diseased. Another plot from which the shaws had been 

 cut about the same time, but which were dug soon afterwards, 

 and left on the surface to ripen, remain still perfectly sound. This 

 seems to indicate both that the disease does not originate in the 

 leaf or stem (for in this case the stems were entirely cut otf be- 

 fore there was the slightest manifestation of disease in either stem 

 or tuber), and that it originates in the tuber only under certain 

 circumstances, for in the one case where the potatoes were left in 

 the ground, they became diseased; and in the other, where they 

 had been dug before the disease appeared, the disease did not de- 

 velop itself The constitution of the potato seems lor a time to 

 have become weakened; some of the tubers growing from the 

 same set may be more predisposed to disease than others; these, 

 under certain unfavorable circumstances of atmospheie acting 

 upon the soil, become diseased. In this state the weakened tis- 

 sues of the tuber are a fit receptacle for parasitic life, which, 

 while it is the consequence and not the cause of the disease, by its 

 rapid development materially hastens the decay of the plant. The 

 fungus beginning in a single diseased or weakly tuber spreads 

 rapidly up the stem, filling up in its progress the respiratory or- 

 gans of the plant, and at the same time putting a stop to the de- 

 scent and consequent formation of fibrous tissues in every tuber 

 at the same stem. A due supply of carbon is necessary for the 

 formation of fibrous tissue to strengthen the frame of the potato, 

 and it is elaborated from the atmosphere and transmitted to the 

 tuber by the healthy function of the leaves and stem. This ela- 

 boration of carbon cannot take place without the aid of sunlight, 

 and, both last year and this, the disease made its appearance in 



