472 



CONSTRUCTIVE AND DESTRUCTIVE METABOLISM 



is impossible to be certain whether these simple changes may not be 

 the result of complex decompositions and reorganizations occurring in the 

 interior of the protoplast. 



Starch always originates in special plastids or chromatophores, but no 

 definite organs seem to be concerned in the formation of fats, which like 

 many other products may accumulate in the cell-sap, so that the locality 

 where fat is found affords no indication as to the place of its formation. 

 The importance of the exchanges occurring between the cell-sap and plasma 

 as the means by which metabolic changes may be indicated or regulated 

 will be discussed later (Sect. 93). 



As examples of non-nitrogenous metabolism, the following table giving the 

 composition of seeds and seedlings of maize and hemp may be given. The values 

 for maize are from Boussingault l , who germinated twenty-two seeds weighing 

 8-636 grm. in darkness on pumice-stone and analyzed the seedlings after fifteen 

 days. Similar analyses were made with the same weight of grains of maize, including 

 the integuments. 



Detmer's 2 analyses of hemp seedlings were obtained in a similar manner and 

 are as follows : 



1 Boussingault, Agron., Chim. agric., &c., 1868, T. IV, p. 261. 



a Detmer, Physiol.-chem. Unters. iiber die Keimung olhaltiger Samen, 1875, p. 40. According 

 to Leclerc du Sablon (Rev. gen. d. Bot., 1895, T. vn, p. 210), a little glucose and cane-sugar are 

 formed during germination. Cf. also Frankfurt, Versuchsst., 1894, Bd. XLIII, p. 157. For further 

 literature on chemistry of germination, see Sect. 109. 



