22 TKANSLOCATION OF PLANT FOOD IN WHEAT SEEDLINGS. 



FIBER. 



The fiber in 100 seeds amounts to 0.0785 gram. At the end of 15 

 days there is a decrease of fiber in the residual seed of about 6 per 

 cent, practically the same conditions obtaining in the control as in 

 culture media, as is shown in Tables 7 and 8. There is, therefore, 

 no apparent absorption of the nonembryo fiber from the seed by 

 the plant in 15 days. On the other hand, the axes in 5 days 

 formed twice as much fiber as was in the seed, and in 15 days the 

 amount was from 5 to 7 times that in the seed, the fiber formation 

 increasing steadily, as may be seen from the tables. There is a 

 slightly greater amount of fiber found in the axes of plants grown 

 in the nutrient solutions than in those in the water culture, owing 

 to the greater growth which the seedlings made under the stimulus 

 of the plant food. However, the per cent of fiber in the axes is 

 approximately the same irrespective of the kind of solution in 

 which the plants were grown, as shown in the tables. The fact that 

 the sugars increased to such an extent only at last to disappear 

 almost entirely (see p. 28), and that the pentosans also increased 

 and then remained practically stationary (see p. 26), would seem 

 to indicate that a large part of the sugar is finally converted into 

 fibrous material, some of it possibly passing through the pentosan 

 stage. According to Ravenna and Cereser, 1 the simple sugars exert 

 a great influence on the formation of pentosans, and, according to 

 Calabresi, 2 there is a very close, though not genetic, relation between 

 the pentosans and cellulose. 



i Atti. R. Accad. Lincei, 1909, 18 [v] : 177. ^ 2 Stazioni sperimentali agrarie, italiane, 1906, 89: 69. 



