THE FIRST LEAVES 



17 



The stem increases in length by the simultaneous elongation 

 of several internodes, as shown by Fig. 11. It will be noticed 

 that in the plant figured the greatest increase in 

 length js neither in the oldest nor the youngest 

 internodes which are growing at all, but in an inter- 

 mediate region. 



Every portion of the entire shoot, shown in the 

 figure, has elongated except the interval 21-22. 



Counting from the top the lengthening of several 

 of the segments is as follows : 



a plumule is found well developed in FIG. 11. Growth in a hori- 

 zontal shoot of hedge 

 the seed, it was formed after the coty- b i n dweedi 



ledons. In those plants which have so 



much food stored in the cotyledons as to 



render them unfit ever to become useful 



foliage leaves, as in the pea, there is 



little or nothing in the color, shape, or general appearance of 



the cotyledon to make one think it really a leaf, and it is only 



by studying many cases that the botanist is enabled to class all 



the shoot divided by 

 ink marks into 22 equal 

 segments ; I>, the same, 

 twenty-four hours later. 

 After Bonnier and Sablon 



1 Convolvulus sepium. 



