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A TEXTBOOK OF THEORETICAL BOTANY 



some reciprocal outgrowth of the endosperm itself. The character is found 

 almost universally in the Annonaceae and in Myristicaceae, Araliaceae 

 (Fig. 1370) and in many Palmae. In Myristica and in the Palms, it is the 



Fig. 1370. — Ruminate endosperms in members of the 

 Araliaceae. A and B, Hedera helix. C, Artliro- 

 phyUiim diversifolium. D, Polyscias ornijolia. 

 {After Harms.) 



nucellus which grows inwards, but this is not a true perisperm since it con- 

 tains no reserves. In Annonaceae the infoldings are due to ingrowths of the 

 integuments on the two flanks of the seed, where they are free (Fig. 1371). 

 The seed coat is rigid in the plane of the funicle and in this plane there are no 

 folds, but at the sides they appear in basipetal order (Fig. 1372). The efl'ect 

 is greatly to increase the surface of contact between endosperm and testa, 

 which may be important in the movement of food reserves and of water 

 during the maturation of the seed (Fig. 1373). The greater extent of surface 

 may also have importance in the solution of these unusually massive reserve 

 tissues at germination, since there is evidence that the peripheral layer of 

 the endosperm may be the source of the hydrolytic enzymes which attack 

 its reserves during germination. The single furrow in Grass seeds may be 

 regarded as a simple form of rumination. 



From the micropylar position of the oosphere in the embryo sac and 

 the downward development of the embryo, it follows of necessity that the 

 radicle of the mature embryo is directed towards the micropyle, from 

 which, or in its neighbourhood, it eventually emerges, and that the plumule 



