182 W. RALPH JONES 



There remains the possibility of a quantitative difference in 

 the amount of enzyme present in the different parts of the cotyle- 

 don. To investigate this, five lots of material were prepared as 

 follows: (1) the entire pea, ground; (2) the embryo, without the 

 testa, ground; (3) the testa, ground; (4) peripheral cells of the 

 cotyledon, filed from the convex face; (5) cells from the interior 

 of the cotyledon, excavated with a dental "burr." Half a gram 

 of each powder was treated with 10 cc. distilled water for an hour, 

 and filtered. One gram of pea starch, thoroughly washed and 

 dried in a desiccator, was dissolved, with boiling, in 160 cc. distilled 

 water, 4 cc. of the filtered extract from each of the five lots were 

 mixed with 16 cc. of the starch solution. A control was made by 

 adding 4 cc. of distilled water to 16 cc. of the starch solution. 

 The mixtures were then kept at 50°C. until all starch had disap- 

 peared. 



The starch was entirely digested in these solutions in the fol- 

 lowing periods, approximately: 10 



1. Entire pea, nine hours. 



2. Embryo, without testa, eight and one-half hours. 



3. Testa, nine hours. 



4. Peripheral cells of cotyledon, three hours. 



5. Internal cells of cotyledon, nine hours. 



At the end of nine hours the control showed no change. 



This experiment shows clearly that there is a much greater 

 enzymotic activity in the extract from the peripheral cells of the 

 cotyledon than in any of the others. The difference may be due 



(1) to an actually greater amount of enzyme present in these cells, 



(2) to the presence of some inhibiting or retarding agent in the 

 cells of the internal region, or (3) to the presence of an accelerating 

 agent in the peripheral region. 



Lack of time prevented the further experimental study of this 

 interesting problem, but it is hoped that the points here brought 

 out may be of use in ultimately gaining an insight into this some- 

 what peculiar sequence in cell activity. 



10 Owing to the presence of a protein giving a greenish reaction with the iodine, 

 the exact time required for the hydrolysis of the starch could not be made out. 



