August 3, 1917] 



SCIENCE 



117 



fered in regard to the length of the stem, which 

 was in the three experiments 2 (A), 1 (B) and 

 0.5 cm. (C), respectively. The leaves dipped 

 with their apices in water. The results are 

 given in Table I. In this table we call the dif- 

 ference in the mass of shoots produced in the 



It is almost impossible to split the living 

 stem so perfectly that the two pieces are abso- 

 lutely equal and in this way an error creeps in 

 which can only be eliminated by a large num- 

 ber of experiments. In 19 different sets of ex- 

 periments the leaves without stems produced 



TABLE I 

 DUEATION OF EXPEKIMENT 23 DATS 



leaves without and with stems the inhibiting 

 action of the stem. This quantity should 

 equal approximately the sum of the mass of 

 shoots produced in the axil of the leaf at- 

 tached to the stem plus the increase in weight 

 of the stem attached to the leaf during the 

 duration of the experiment. The ratio of the 

 two values should therefore approximately 

 equal 1 (Table I.). 



The experiments show that within the limit 

 of error the mass of the stem increased in such 

 a way as to approximately equal the inhibiting 

 effect of the stem on shoot production in the 

 notches of the leaf. The mass of roots pro- 

 duced in the leaves is neglected since it is 

 small compared with the mass of stems. 



27.898 grams of shoots and the leaves with 

 stems 9.797 grams. The inhibiting action of 

 the stems, i. e., the difference in shoot produc- 

 tion between the leaves without stems and 

 their sister leaves with stems was therefore 

 18.101 grams. According to our theory the 

 weight of the stems which were left attached 

 to the leaves should have increased by the 

 same amount. The actual increase in the 

 weight of the half stems attached to the one set 

 of leaves was in the same time 16.695 grams. 

 This includes the increase due to shoot pro- 

 duction in the axil of the leaf, which was 

 slight, amounting in all to less than 1.5 grams. 

 The two values, 18.101 and 16.695 differ by 

 8.5 per cent. 



