102 



PLANT GROWTH SUBSTANCES 



(fats) was then made, and this revealed the fate of at least part of the 

 reducing sugars. As shown in Figures 3 and 4, the inhibitor causes a 

 lar<^e increase in the content of fats in the sections. The extent of the 

 reaction is proportional to the concentration of the inhibitor. The action 

 of iodoacetate is in the same direction but less marked. In the case of 

 arsenite the final fat level is equal to the initial value, but in the case of 

 fluoride there is an actual formation of additional fat. These phenomena 



-UNTREA TED C ONT ROL 



WATER CONTROL 



_L 



_L 



CONCENTRATION OF ARSENITE 



EFFECT OF ARSENITE ON 



ETHER SOLUBLES 



4«I0-*M. 



Figure 3. Changes in the fat content (neutral ether soluble fraction) of 

 pea stem sections after 24 hours in indoleacetic acid i mg. per liter with and 

 without sodium arsenite. The As concentration giving 50 per cent growth 

 inhibition was i x io~^M. 



indicate far-reaching metabolic changes, the occurrence of which is 

 concealed by the constancy of the oxygen consumption. 



Still other far-reaching changes take place in the nitrogen compounds. 

 Analyses for proteins, amino acids, amides, and ammonia, of which a few 

 selected data are given in Table 3, show the following facts: i) as the 

 sections are maintained in water the amino acids are consumed; 2) this 

 consumption is more complete if the sections are actually growing in 



