FOOD 127 



vetch is intensified to different degrees by saccharose, glucose 

 and maltose, the last mentioned being less effective than the 

 others. Spoehr,* from his investigations on the carbohydrate 

 economy of the Cactaceac, concludes that the rate of respiration 

 is not controlled by any one group of sugars, thus hexose 

 sugars, which often are considered to be of exceptional im- 

 portance in respiration, occur in the Cactacese in variable 

 amounts in varying conditions of existence and sometimes 

 may be almost absent, but the respiration intensity is not 

 thereby reduced in any marked degree. In conditions which 

 involve a poor supply of hexose sugars, the polysaccharides 

 are consumed in the respiratory processes and such con- 

 ditions are possibly connected with the formation of pento- 

 sanes. The conditions referred to are temperature and water : 

 a low water content accompanied by a high temperature 

 bring about a decrease of monosaccharides and an increase of 

 polysaccharides and of pentosanes, whilst the contrary con- 

 ditions, a high water content and low temperature, are as- 

 sociated with an increase of monosaccharides and a decrease 

 of polysaccharides and of pentosanes. 



With regard to the proteins, Palladin f has shown that 

 during the germination of wheat in darkness the total protein 

 content and the soluble carbohydrates diminish, whilst the 

 evolution of carbon dioxide and proteins insoluble % in pepsin, 

 increase in amount. As development proceeds, the carbo- 

 hydrates, which originally were abundant, become depleted 

 and the decomposition of protein is less vigorous and may even 

 cease. Hence in the later stages of germination there is a 

 more vigorous respiration in conditions of low protein con- 

 tent than in the early phases of germination when more 

 protein occurs. The proteins which disappear are those of 

 the reserve food, not those which are presumably members 

 of the protoplasmic complex and which show a direct relation 

 to the amount of carbon dioxide evolved. This is shown in 

 the following table which relates to wheat germinating at 



* Spoehr : " Carnegie Inst. Pub.," 1919. No. 287. 

 t Palladin : " Rev. gen. Bot.," 1896, 8, 225. 

 I The solubility being determined in vitro. 



