578 TKAXSACTIONS AND PROCEEDINGS OF THE [Skss. lvu 



simple structuves. This ditference, however, he explains 

 by the remark that, while he conducted his observations on 

 cultivated plants, those described by Hildebrand were wild. 



Buchenau (i.), who seems to have employed wild plants 

 in his researches, states that the first stem leaves are 

 generally tripartite and very seldom simple. 



Bkaxchixg. — Xo branches are formed during the first 

 year in the axils of either the cotyledons or the first few 

 plumular leaves, but the higher trifoliate leaves, and all 

 leaf organs higher up the axis, bear in their axils spine- 

 branches. These -are tlie only branches which appear 

 during the first year, but in the spring of the second year 

 the cotyledons and lower leaves give rise to axillary 

 branches of another kind which are not spine-structures, 

 but are, on the other hand, indefinite as regards their growth. 

 At the same time similar, but in this case accessory, 

 indefinite branches arise higher up the stem between the 

 spine-branches and the leaves from the axils of which 

 they spring. 



After the commencement of the second year, therefore, 

 a plant of Ulcx exhibits two distinct kinds of branches, 

 viz. : — the spine-branches, which are all axillary structures 

 arising in the axiles of the spine-leaves ; and the indefinite 

 branches, of which the lower three or four are axillary in 

 the axils of the cotyledons and lower leaves, while the 

 higher are accessory, arising immediately below the axillary 

 spine-branches, i.e. between them and their axillant leaves. 



Leaf Arrangement. — The arrangement of the leaves is 

 not the same on both these branch systems, and the leaves 

 themselves also differ in their foini and texture at least in 

 the early stages of both. The first leaf organs borne on 

 the spine-branches are two lateral prophylls, which take 

 tlie form of spine-leaves placed opposite each other. The 

 tliird leaf is ]jlaced in the median plane posteriorly, and is, 

 according to Wydler (viii.), the first leaf of a 3 emprosthro- 

 dromous spiral of which he has observed three cycles, the 

 second alternating with tlu; first, while the third is placed 

 directly over it, though in some cases this third cycle is 

 absent and is replaced by a '^ spiral. 



in other specimens he finds the \ spiral entirely absent, 

 while the '^ fi)llows immediately on the two prophylls. 



