756 NATURAL SCIENCE. 



Dec. 



and subterranean cotyledons in the same genus ; Clematis graveolens 

 has aerial cotyledons like all the other specimens of Ranunculaceae 

 described, but in C. recta (Fig. 21) they are fleshy and do not leave the 

 seed, and as usual in such cases the first leaves are small and soon 

 drop, in the figure they have already fallen. The same occurs in the 

 genus Phaseohis, where P. vulgaris has its cotyledons borne up on a 

 long hypocotyl, while in P. mnltiflorus they remain below ground in 

 the seed. In Clematis, however, the aerial cotyledons are foliaceous, 

 but in Phaseohis they are thick and fleshy, wrinkled and turned to 

 one side of the stem, and only a pale green, looking as if they ought 

 never to have left the seed, and the hypogaeal were the normal state. 

 In Erythrina monospernia, also a member of the tribe Phaseoleae, the 

 cotyledons are aerial, but thick, fleshy, and pale yellow, while in 

 E. suherosa and E. vespertilio they are subterranean. 



In Chimonanthis, belonging to the Calycanthaceae, a small order 

 closely allied to the Ranunculaceae, the fleshy cotyledons fill the seed, 

 but are aerial, becoming foliaceous and persisting for more than a year; 

 the two following pairs of leaves are small and perish early. 



The cotyledons of Anona palustvis (Anonaceae) are aerial and 

 closely resemble the true leaves, but in several species of the genus 

 they never leave the seed, but are torn from the axis during 

 germination. 



In spite of the great diversity of the fruits and seeds in the 

 Cruciferae, the cotyledons may be grouped under a few leading types. 

 They may be broad and entire, as in Matthiola incana (Fig. 3), or 

 broad and emarginate, as in the radish, cabbage (Fig. 18), or mustard. 

 The linear form of Heliophila is unusual, while the spathulate type 

 represented by Bunias orientalis seems to be due to growth after germi- 

 nation, as the cotyledons are narrow and spirally coiled in the seed. 

 Schizopetalon walkeri and the common cress {Lepidium sativum) are 

 exceptional in having divided cotyledons (Fig. 22). In the former they 

 are bipartite, looking like four narrow cotyledons, and it is suggested 

 that this may be a device for getting rid of the seed, as there seems 

 to be some difficulty, the narrow arms having to struggle out through 

 a small orifice. In the cress, on the other hand, the two lobes of 

 each cotyledon help to fill up the extra large seed. 



The cotyledons of Viola tricolor (Fig. 23) closely resemble those 

 of V. paliistris (Fig. 24), but the shape of the leaves is very different 

 in the two cases. 



Hibiscus phceniceus (Malvaceae) has dimorphic seedlings, one form 

 retaining the simpler form of leaf much longer than the other. 



In Linuiii monogynum (Lineas) (Fig. 25), the cotyledons are much 

 longer and broader than the following leaves, an unusual circum- 

 stance, but recurring occasionally, as in Olea cuspidata (Fig. 26) and 

 Hakea acicularis (Proteaceae). 



Under Leguminosae we may notice the gradual reduction of the 

 leaves to spines in the gorse {Ulex euvopans) (Fig. 27) ; and the appear- 



