1 8 Sargant. — Theory of the Origin of Monocotyledons 
pairs. Thus the tetrarch root is formed according to Van 
Tieghem’s type i, and the distinction between main and 
lateral bundles is indicated only by the slight want of symmetry 
due to the smaller size of the lateral traces (PI. II, Fig. 9). 
Muscari neglectum . The sheath of the cotyledon contains 
four or more lateral bundles in addition to the two main 
bundles. In two of the seedlings cut (A 5 and A 7 ) all the 
lateral bundles except two disappear before the transition 
begins : inserting themselves for the most part on the two 
which remain. The transition to a tetrarch root then proceeds 
regularly as in Diagram II. 
In seedling A 2 , however, two of the supernumerary bundles 
fuse with each other and enter the stele as a fifth trace. This 
behaves like the others, and a pentarch stele is formed accord- 
ing to Van Tieghem’s type 1. 
The forms just described form an unbroken series which 
connect the Albuca structure, or type 4, with the simple and 
no less definite symmetry shown in Diagram II and PI. II, 
Figs. 8 and 9. In this transition two lateral traces of the 
cotyledon take an equal share in forming the root-stele with 
the two main traces. All four traces behave alike, following 
Van Tieghem’s type 1. 
The same symmetry in essentials is characteristic of the 
transition in Eucomis nana , Jacq., but with one interesting 
variation. 
In Fig. 5 on PI. II the two main bundles M x and M 2 are 
seen to be united by a common protoxylem group, which has 
already begun to turn outwards. The lateral bundles are still 
quite distinct from the main bundles and from each other. In 
this case the fusion of the two main bundles has only just 
occurred : they were distinct -03 mm. above the section drawn 
in the figure. But in Eucomis nana the main bundles are 
united throughout the cotyledonary sheath. In its upper 
part they resemble a single massive bundle ; lower down this 
opens out into a double bundle with distinct phloem and 
xylem but a common protoxylem group. Just above the 
