128 



VEGETABLE LIFE AND WOEK. [SECTION 16. 



428 



Aceumlent, that is, the edges of the flat cotyledons lie against the radicle, 

 as in Fig. 425, 426. In another they are 



Incumbent, or with the plane of the cotyledons brought up in the opposite 

 direclion, so that the back of one of them lies against 

 the radicle, as shown in Fig. 427, 428. 



391. As to the situation of the embryo with respect 

 to the albumen of the seed, when this is present in any 

 quantity, the embryo may be Axile, that is occupying 

 the axis or centre, either for most of its length, as in 

 Violet (Fig. 429), Baibeiry (Fig 48), and 

 Pine (Fig. 56) ; and in these it is straight. 

 But it may be variously curved or coiled 

 in the albumen, as in Helianthemum 

 (Fig. 430), in a Potato-seed (Fig. 50), 

 or Onion-seed (Fig. 60), and Linden 



(Fig. 414); or it maybe coiled around 429 430 430'' 



the outside of the albumen, partly or into a circle, as in Chickweed (Fig. 

 431, 432) and in Mirabilis (Fig. 52). The latter mode prevails in Campylo- 

 tropous seeds. In the cereal grains, such as Indian 

 liM « Corn (Fig. 67) and Rice, 430 "), and iu all other 

 '§0^^ Grasses, tlie embryo is straight and applied to the 

 431 432 outside of the abundant albumen. 



392. The matured seed, with embryo ready to germinate and reproduce 

 the kind, completes the cycle of the vegetable life in a phanerogamous 

 plant, the account of which began with the seed and seedling. 



Section XVI. VEGETABLE LIFE AND WORK. 



393. Tlie following simple outUucs of the anatomy and physiology of 

 plants (3) are added to the preceding structural part for the better prepar- 

 ation of students in descriptive and systematic botany ; also to give to all 

 learners some general idea of the life, growth, intimate structure, and action 

 of the beings which compose so large a part of organic nature. Those who 

 would extend and verify the facts and principles here outlined will \ise the 

 Physiological Botany of the " Botanical Text Book," by Professor Goodale, 

 or some similar book. 



ElG. 427. Seed of a Sisymbrium, cut across to show the incumbent cotyledons. 

 428. Embryo of the same, detached whole. 



FlQ. 429. Section of seed of Violet ; anatropous with straight axile embryo in 

 the albumen. 430. Section of seed of Rock Rose, Helianthemum Canadense ; 

 orthotropous, with curved embryo in the albumen. 430 ". Section of a grain of 

 Rice, lengthwise, showing the embryo outside the albumen, which forms the 

 principal bulk. 



Pig. 431. Seed of a Chickweed, oampylotropous. 432. Section of same, show- 

 ing slender embryo coiled around the outside of the albumen of the kernel. 



