690 Bancroft. — Note on Vegetative Reproduction in 
At each dichotomy of the tuber axis, and in the plane at right angles to it, 1 
arise two very short branches, which are really exogenous in origin but 
present a semi-endogenous appearance due to the general enlargement and 
hypertrophy of the tissues of the tuber (Text-figs. 5 and 6 ). 
The vascular supply to the dorsal branch separates from the stele of 
the tuber immediately before its bifurcation to supply the two vegetative 
branches. The ventral branch is subtended by a leaf, and its vascular 
Text-fig. 5. S. chrysorrhizos. A and b show diagrammatically two transverse sections of an 
‘underground tuber’, A near the base, and B near the apex, br., branch; d., dorsal rhizophore ; v., 
ventral rhizophore; st stele of axis; br.v.s ., vascular supply to branch; v.v.s., vascular supply to 
ventral rhizophore; r., root-hairs; e. } trabecular endodermis. In B the dorsal rhizophores accom- 
panying both branches do not appear at this level, x 32. 
supply arises from one branch of the stele immediately after bifurcation 
has taken place. These short branches are undoubtedly the rudimentary 
dorsal and ventral rhizophores, which remain short and undeveloped since 
the tubers are already embedded in the ground. The vascular supply, in 
its passage to the rhizophores, has the characteristic endodermis of the 
stem-stele. 
The rhizophores have somewhat enlarged rounded ends ; a similar 
enlargement in ordinary rhizophores is, according to Hofmeister, 2 due to 
1 Cf. Velenovsky’s description of ‘ tetrachotomy 1. c., p. 260. 
2 Hofmeister, 1. c., p. 384. 
