THE POTATO. 155 



IV «ras about the year 1710 that the potato began to spiead in Ger- 

 many, and that it there became a plant in common use ; it had, in- 

 deed, before this time been cuhivated in gardens ; and had even 

 made its appearance at the tables of the rich some time previously. 

 The severe dearth of the years 1771 and 1772* seemed necessary 

 to lead the Germans to cultivate this useful plant upon the great 

 scale. From this time it was shown that it was a substitute for 

 bread ; and once fairly introduced, men were not long of perceiving 

 the many recommendations which it possesses as an article of food. 

 In fact, of all the useful plants which the migrations of communi- 

 ties and distant voyages have brought to light, says M. Humboldt, 

 there is none since the discovery of the cereals, that is to say, from 

 time immemorial, which has had so decided an influence upon the 

 well-being of mankind. In less than two centuries it may be said 

 literally to have overspread the earth, or to have been welcomed in 

 every country suited to its cultivation, so that at the present day it is 

 found growing from the Cape of Good Hope to Iceland and Lap- 

 land. " It is an interesting spectacle," adds the illustrious traveller 

 quoted, " to see a plant, a native of mountains situated under the 

 equator, advance towards the pole, and growing even more hardily 

 than the grasses which yield ns grain, brave the inclemencies of the 

 North, "I The potato, like all other tubers, is a collection, an exu- 

 berance which is evolved upon the subterraneous stems. Its varie- 

 ties, which are very numerous, present rather remarkable differences 

 in regard to size, form, color of the surface and of the interior, taste, 

 and the time which they require to come to maturity. 



Next to water, fecula or starch is the principle which predominates 

 in the potato, but it also contains a certain quantity of azotized mat- 

 ter. Vauquelin has published a detailed account of the soluble mat- 

 ters which are met with in the potato, and which, strange to say, 

 have been neglected in the greater number of analyses of this useful 

 vegetable which have been published. In 100 parts of potatoes he 

 found : asparagine 0.1, albumen 0.7, azotized matter not defined 0.4, 

 citrate of lime 1.2, and undetermined quantities of citrate of potash, 

 free acetic acid, phosphate of potash, and phosphate of lime. 



In examining forty-eight varieties of potato he found that they 

 contained in 100 parts : first, from 1 to U of pulp ; second, from 2 

 to 3 of soluble or extractive substances ; third, from 20 to 28 of 

 starch ; fourth, from 67 to 78 of water.| 



In a variety grown in the neighborhood of Paris, Henry found the 

 following ingredients, viz : pulp 6.8, starch 13.3, albumen 0.9, un- 

 crystallizable sugar 3.3, acids and salts 1.4, fatty matter 0.1, and 

 water 74.2=100.0. 



The proportion of starch varies considerably in the diflferent va- 

 rieties ; M. Payen has ascertained the extent of this diversity in a 

 certain number of varieties grown in the same soil and under the 



* Thaer, Principes raisonn6s d'Agriculture I. iv. p lift, 



i Humboldt, op. cit. t. ii. p. 463. 

 TWnard'a Chemistry, vol. v. p. 82. 



