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THE FARMER'S MAGAZINE, 



energy of life ; but as the root consists chiefly of starch, 

 which is not capable of entering into the plant, Nature 

 has provided for the formation of a decomposing agent 

 (which is known as diastase) around the germ, and this 

 body changes the starch of the potato into gum or sugar, 

 in which form it is useful as food for the young germ. 

 This powerful agent is formed in other seeds, and the 

 value of the process of malting barley depends upon its 

 formation. The reader will probably be more familiar 

 with it when I say it is a body which is produced in 

 malt, and which is its active principle or real strength. 

 Naturally, this is formed only around the germ of the 

 potato, but Professor Way discovered that the disease 

 caused it to be formed throrighout the plant. We are 

 all aware that cold can so alter the composition of some 

 portions of the potato as to produce this agent through- 

 out the root. This is quite unnatural ; for in the healthy 

 growth of the potato this body is only found around the 

 germ or eye, and never throughout the root. To prove 

 that cold will effect this change, I need not give you any 

 stronger proof than the influence of frost upon potatoes. 

 When potatoes have been exposed to the frost, and they 

 are afterwards boiled, they become sweet to the taste ; 

 this sweetness is due to diastase having been formed, 

 which has turned the starch into sugar. This chemical 

 change which occurs in the root is known to have been 

 produced in the growing plant by the disease, and this 

 is the earliest effect observed. 



The presence of this active decomposing agent is 

 enough to account for all the changes which naturally 

 occur. The plant has thus been charged with the ele- 

 ments of decay, and it only needs favourable circum- 

 stances to develope the destructive powers which are 

 bidden there. It is well known that moisture and 

 warmth caused rapid decay ; but when the roots were 

 kept dry and cool, they remained good for a longer 

 period than usual. As soon as this agent was formed 

 in the sap, it was diffused by the circulation going on in 

 the plant, and thus became generally distributed. This 

 early formation also accounts for the disposition to 

 sprout which has been manifested so much earlier than 

 usual. We may also gather another explanation as to 

 the opposing opinions held, whether the stalk or the 

 leaves first become affected. The change was without 

 doubt produced in the sap as it circulated through the 

 leaf: if its movements happened to be slow, the leaves 

 would probably be the first to show signs of decay ; 

 whilst if the motion was rapid, the sap would pass on into 

 the stem, and there commenced its decomposing influence. 

 This view of the case is somewhat confirmed by the 

 fact that the jiotato disease has been jiroduced arti- 

 ficially, as recorded by Mr. Graham in the Journal of 

 the Hoyal Agricultural Society, vol. vii., page 372. 

 It is also woriliy of notice that Professor Way showed 

 that potatoes might appear perfectly sound, and yet if 

 this agent had been formed they were sure to give evi- 

 dence of the disease. Thus, in some cases, under care- 

 ful management, the diastase was kept inactive for 

 months in those roots which were preserved cool and 

 dry, whilst to all appearance they were free from djs- 

 cn^9, After the tissues of the plant become acted upon. 



and their decay has commenced, then fungi and animal 

 life come under observation; but they never precede 

 the chemical change already described, and must there- 

 fore be looked upon as subsequent results of still later 

 occurrence, and certainly not in any way the original 

 cause of decay. This explanation of the disease appears 

 to my mind clear and simple, and it does not need the 

 adoption of any novel views, for the results are traced to 

 the action of a decomposition arising from chemical 

 changes produced in the sap by atmospheric agency. 



This is a very brief description of the potato disease ; 

 and now we may notice the means adopted to prevent 

 its occurrence ; but this embodies the general manage- 

 ment of the crop. The entire system of culture has now 

 for its primary object to avoid this disease, or to miti- 

 gate its attack. There are no special means adopted to 

 prevent this disease, but such as come under our notice 

 in the management of the potato crop in different dis- 

 tricts, to which I now draw your attention. 



The culture of early potatoes for the London market 

 is a special branch of the practice, and needs very par- 

 ticular management to ensure success. Three conditions 

 appear necessary for success : a favourable climate ; a 

 dry, friable, and fertile soil ; combined with good 

 management. The districts most noted for this descrip- 

 tion of potato are Cornwall and Lancashire, and in each 

 of them proximity to the sea is of essential importance. 

 The reason for this is that the temperature near the sea 

 (especially on the western side of England) is less sub- 

 ject to variation, and the plants growing in these neigh- 

 bourhoods are thus protected in an unusual degree from 

 the influence of frosts. Temperature is, therefore, the 

 chief influence which gives superiority to these sea-sido 

 districts. 



The character of the soil is as important as the climate, 

 and the first condition is that the soil must be loose and 

 friable. For this reason, the granite and greenstone 

 soils of Cornwall, and the red sandstone soils of Lan- 

 cashire, from possessing these characters, are very 

 favourable for encouraging a free and unrestrained 

 growth, and enabling the roots to spread freely in search 

 of nourishment. Dryness of the soil is equally neces- 

 sary ; for in like manner as wet soils are cold, so also 

 are dry soils warm, and this warmth is of extreme im- 

 portance for producing growth in the spring. The in- 

 fluence of the sun upon sandy or gravelly soils is also 

 very prompt ; and in this manner the plant receives 

 powerful supplies of this stimulant to growth. The last 

 condition named, or the fertility of the land, is a mani- 

 fest necessity ; for rapid growth needs a liberal supply 

 of food, and such as only fertile soils can yield. Thus 

 the character of soil required embodies all those quali- 

 ties which regulate luxuriance of produce ; and when 

 these are available under a favourable climate, then we 

 have a soil suited for the growth of very early potatoes, 

 and of course worth a very high rent. The rent in the 

 districts already named range from £10 to £15 per 

 acre, and even at these prices the land yields very pro- 

 fitable crops. I am now only referring to the earliest 

 class of soils, such as? are found near Penzance ancl 

 I Morecombe Bay. 



