SEEDLINGS. 



177 



12 Tripartite; lateral segments bifid. 



13 Similar. 



14 Cuneate, tripartite, lateral segments unequal. 

 Some cotyledons are broad, as in Impatiens, Fig. 37 ; in other 



species we find narrow cotyledons and broad leaves, as in Meni- 

 spermum, Fig 38, while in others the cotyledons are broad and 

 the leaves narrow, as in Hakea, Fig. 39. 



In some cases instances of broad and 

 narrow cotyledons may be found in the 

 same family, as in Chickweed, and Pink, 

 and sometimes even in the same genus, 

 as Galium Saccharatum and Gallium 

 Aparine. In some cases, again, the two 

 cotyledons are unequal, as in Mustard, 

 Cabbage, etc. Sometimes the two halves 

 of each cotyledon are unequal, as in 

 Geranium, and indeed their variety ap- 

 pears to be very considerable. 



Turning now to the embryo, some ex- 

 Fig. 39. -Seedling of ^a^.a^eedingly interesting descriptions of its 

 acicularis, half nat. size, growth are given, as, for example, in Acer, 

 Fig. 40, the embryo originates in a short tubular cavity opposite 

 the micropyle, and is at first straight, with an extremely short 

 tubinate radicle, and ovate, obtuse^ closely adpressed cotyledons. 



6 



Fig. 40. — Acer Pseudo-Plaianus. Sections of seed in seven successive 

 stages, showing growth of embryo, x 3. 



As growth continues the embryo extends itself along the lower 



Imtbrnational Journal of Microscopy and Natural Scienck. 



New Series, Vol. III. n 



