66 THE POTATO CROP. 



would be 'legion' if we were thoroughly acquainted with 

 all the species, in their different stages of development, 

 preying upon this useful esculent ; and although, in the 

 foregoing statement, no attempt has been made to give 

 undue importance to their agency, there can be no ques- 

 tion that insects often injure the potato crops to a great 

 amount." 



The large consumption of the potato by the inhabitants 

 of the different countries in the northern temperate zone 

 as an article of food, and also for economic purposes, has 

 caused its composition, organic as well as inorganic, to 

 be well investigated by both our own and continental 

 chemists. A wider difference in the results obtained is 

 noticeable in reference to this than to any other of our 

 " Farm Crops/' due, probably, to the greater number of 

 varieties of the potato in cultivation, and to the greater 

 influences exerted upon them by the various soils and 

 climates of the countries or districts in which they were 

 grown. The proportions of stems to tubers are liable to 

 great variation; on the average of a large number of 

 trials, they may be taken at about two-fifths, or as 2 is 

 to 5. The percentage of water contained in the tubers is 

 influenced greatly by the state of maturity of the tuber at 

 the time of examination, and also by the variety. Thus, 

 in Dr. Fromberg's elaborate investigation of the com- 

 position of the potato, 1 the least ripe were found to contain 

 76 per cent, of water, while the ripest only contained 68 

 to 70 per ^ent. Again, the Irish Cup variety gave 74 

 per cent., while the " Buffs/' grown under exactly similar 

 conditions as to soil, treatment, &c., gave 77 per cent. 

 The mean of fifty-one determinations in Professor John- 

 ston's laboratory was 76 per cent.; the mean result of 

 Korte's analyses of fifty-seven varieties was 75'1 per cent.; 

 the average proportion of water, therefore, in ordinary 

 samples of potatoes may be taken at about 75 per cent., or 



1 High. Soc. Trans., 1847, p. 637. 



