148 EXPERIMENTAL FARMS. 



These were then submitted to analysis, with the following results : — 



Upper (green) portion . 

 Lower (white) portion . 





Ill 



•93 





•85 

 ■76 



The composition of the dry matter is given in the subjoined table. 



Upper (green) portion . 

 Lower (white) do 





11^ 



8^17 



These data show that in many particulars the composition of the exposed and 

 underground parts is very similar, and that the differences, where such exist, are 

 by no means large. The most notable of these are in the albuminoids and fat. 

 The slightly higher percentage of the former, recorded as occurring in the 

 exposed portion of the carrot, may probably be due to the presence of the green 

 colouring matter (chlorophyll), which contains nitrogen as a constituent, or it may 

 be owing to a development of soluble nitrogen compounds, whose function is to carry 

 this important element from one part of the plant to another to be finally laid up 

 as protein. Further experiments will be made to ascertain if this increase of 

 nitrogen compounds is constant in the parts developed above ground, and also to 

 find out the true character of such compounds. For the present, it will suffice to 

 say that the apparent increased percentage does not in all probability represent any 

 real or material increase in food value. The larger proportion of the consti- 

 tuent here designated as fat, found in the upper part of the root, is undoubtedly due 

 to the presence of chlorophyll, which by the method of analysis is dissolved out 

 and determined with the fat. This increase, therefore, has a fictitious and not a real 

 value. 



It may be concluded from the chemical data of the present experiments that no 

 material difference in food value exists between the two portions. The questions 

 of palatability and digestibility (since disagreeable and poisonous principles are 

 sometimes developed in exposed roots), as well as the economic one of cost of culture 

 and harvesting and weight of crop, are probably the most important to be con- 

 sidered in arriving at a conclusion as to the relative merits of those varieties of roots 

 which grow above and below ground. 



