5i7 
Anatomy of Teratological Seedlings. /. 
group. Each half of the bifurcated cotyledon exhibits a double-bundle 
midrib (Fig. 4), which gradually approaches its fellow until the adjacent 
phloems fuse (Fig. 7). This phase is followed by the reduction in size of 
the adjacent xylems and their fusion, so that a W-shaped structure, in 
Fig. 7. a-e. Henaitricotyl, Type ( 3 . Diagrams showing the initiation of triarchy and its reduction 
to diarchy by fusion. 
Fig. 8 . Tricotyl. Transverse section near approaching fusion between two of the poles 
apex of hypocotyl. and the reduction in the size of the phloem group 
between them. 
which the median portion is much flattened, results. This encloses a small 
phloem group, and is flanked laterally by two other phloem groups (Fig. 5). 
Ultimately, in one case at the base of the cotyledons and in the other in the 
hypocotyl, the fusion of these double bundles becomes more intimate, and 
the enclosed phloem strand dies out (Fig. 6). The two xylems also fuse as 
they pass down the hypocotyl, so that a diarch plate Anally results. In both 
