4o6 Boewig on the Histology and 



over the surface of the fruit, and a blackening of the cotyle- 

 dons with considerable or entire loss of roots and root hairs. 

 These agree with the natural conditions of the plant. The 

 best soil was almost pure sand. Under such conditions seeds 

 germinated in three to four weeks. 



J. Seedling Growth. — The radicle and hypocotyl find their 

 way out of the seed by the micropyle, forcing the shell apart 

 slightly by a single median split, which is, however, not at 

 all extensive and exercises some elasticity, for while the 

 hypocotyl when it first emerges is rather fleshy, it is not 

 nearly so large as it becomes later on when entirely outside 

 the seed. The lowermost part of the hypocotyl is a fleshy, 

 cylindrical body, fifteen mm. long or less, of a pale yellow 

 color, and is glabrous like the rest of the plant. As it 

 emerges from the seed the food substance is rapidly passed 

 from the cotyledons into it, causing it to become very turgid. 

 The food is not reconverted into starch in the hypocotyl, but 

 remains dissolved in the cell sap as sugar. At the lower 

 end is a tiny root that is reduced to a mere conical tooth. 

 In a circular zone above and around this, four side roots 

 typically develop (Plate xxxiii. Fig. 4), which soon out- 

 strip the main root and may reach considerable length. In 

 some seedlings three, two (or even one) side roots develop, 

 which are then somewhat stouter than when there are four. 



Above, the hypocotyl attenuates rapidly into a thin, almost 

 filamentous, but bright green stem, which is at first bent 

 downward with its plumule in the seed (Fig. 4, a) ; it usually 

 rights itself by the time its length equals that of the fleshy 

 portion, and in most cases carries up with it the now empty 

 seed (Fig. 4, b), which, because of its firm, elastic shell, is 

 difficult to strip ofif. One seedling, fully six inches high, still 

 bore the empty seed at its tip with the shell unbroken, and 

 owing to the rather unfortunate growth of two leaves on the 

 portion within the seed, these had become caught and the 

 stem confined within had curled round one and one-half 

 times inside the empty seed. Another seedling, on the other 



