512 ^E^V JEKSEY AGRICULTUEAL COLLEGE 



of plants. The last and slowest of all was the 'Hercules Chib' gourd, 

 which, with its large, ihick-coated seeds, did not make any appearance 

 above the soil until the ^Sth of the month, or nineteen days after tlie 

 sowing was made." 



One of the chief jJoints of study in this experiment was that of the 

 removal of the thick seed-coats with which this class of seeds is pro- 

 vided. The most satisfactory results were obtained by placing the 

 seeds between folds of blotting paper kept constantly moist. The 

 seed-coats open at the end that was attached to the fruit — that is, 

 the "root" end — by the elongation of the primary root, which pushes 

 out, and, if possible, at once turns downward. At the same time there 

 is a lateral growth from the base of the stem, which now consists of 

 a short zone of tissue separating the base of the root from the two 

 large seed-leaves that still remain within the seed-coats. This side 

 growth consists of a cushion of tough cells, without vessels of any 

 kind, developed upon the lower side of the stem and spreading out 

 upon the upper and inner end of the lower half of the seed-coat. 



This curious contrivance was first described by M. Flahault in 

 1877,* and it did not escape the keen eyes of Mr. Darwin, who gave 

 it the name of "'peg,'"' and writes of it as follows :f '"'A heel or peg 

 is developed on one side of the summit of the radicle or base of the 

 hypocotyl, and this holds down the lower half of the seed-coats (the 

 radicle being fixed in the grottnd), whilst the continued growth of 

 the arched hypocotyl forces upward the upper half and tears asunder 

 the seed-coats at one end and the cotyledons are then easily with- 

 drawn." 



As the peg develops it exposes a thick layer of fine, branching 

 hairs upon the side close to the inner coat, while the opposite or free 

 surface is smooth and without hairs. 



•'Each of The outgrowths from the epidermal layer of cells of the 

 lower surface of the peg is irregular in outline, often tortuous, fre- 

 quently abounding with small, disc-like projections, and the extremi- 

 ties are club-shaped. The basal half of each hair is thick-walled and 

 seemingly empty, while the younger and exposed irregularly-br.mch- • 

 ing part is filled with granular protoplasm, which in its disposition 

 and contents is identical with similar structures where glandular 

 exudation takes place. This hairy surface of the peg becomes closely 



* Bull. Soc. Bot. de France, XXIV , page 201. 



f The Power of Moveireat in Plants, pages 102-105. 



