24 



SEEDLINGS. 



rSECTION 3. 



58 



two cotyledons even in a Pine-embryo, but tbese divided or split up con- 

 genitally so as to imitate a greater number. But as leaves are often in 

 whorls on ordinary stems, they may be so at the very beginning. 



40. Monocotyledonous (meaning with 

 single cotyledon) is the name of the one-coty- 

 ledoned sort of embryo. This goes along 

 with peculiarities in stem, leaves, and flowers ; 

 which all together associate such plants into 

 a great class, called Monocotyledonous 

 Plants, or, for shortness, Monocotyls. It 

 means merely that the leaves are alternate 

 from the very first. 



41. In Iris (Fig. 58, 59) the embryo in 

 the seed is a small cylinder at one end of the 

 mass of the albumen, with no apparent dis- 

 tinction of parts. The end which almost 

 touches the seed-coat is caulicle ; the other 

 end belongs to the solitary cotyledon. In 



germination the whole lengthens (but mainly the 

 cotyledon) only enough to push the proximate 

 end fairly out of the seed : from this end the root 

 is formed; and from a little higher the plumule 

 later emerges. It would appear, therefore, that 

 the cotyledon answers to a minute leaf rolled up, 

 and that a chink through which the plumule 

 grows out is a part of the inrolled edges. The 

 embryo of Indian Corn shows these parts on a 

 larger scale and in a more open state (Fig. 66- 

 68). There, in the seed, the cotyledon remains, 

 imbibing nourishment from the softened albu- 

 men, and transmitting it to the growing root 

 below and new-forming leaves above. 



42. The general plan is the same in the Onion (Fig. 60-65), but witn 

 a striking difference. The embryo is long, and coiled in the albumen of the 

 seed. To ordinary examination it shows no distinction of parts. But 

 germination plainly shows that all except the lower end of it is cotyledon. 



For after it has lengthened 



into a long 



thread, the chink from which the 



Fig. 56. Section of a Pine-seed, showing its polycotyledonous embryo in the 

 centre of the albumen; moderately magnified. 57. Seedling of same, showing the 

 freshly expanded six cotyledons in a whorl, and the plumule just appearing. 



Fig. 58. Section of a seed of the Iris, or Flower-de-Luce, enlarged, showing its 

 small embryo in the albumen, near the bottom. 59. A germinating seedling of the 

 same, its plumule developed into the first four leaves (alternate), the first one 

 rudimentary; the cotyledon remains in the seed. 



Fig. 60. Section of an Onion-seed, showing the slender and coiled embryo in the 

 albumen : moaeratelv magnified. 61. Seed of same in early germination. 



