Ter ato logical Seedlings . If. 87 
emerging' simultaneously side by side from the adjacent poles of the xylem 
plates (Fig. 6, d). 
As the tip of the root was approached the parenchymatous layers 
separating the two steles became reduced in number and finally disappeared 
entirely, so that the endodermal layers of the steles came into contact on 
Fig. 5. 1, 2 a and b\ 3 a and b. Hemitetracotylous seedlings. Seedling 2 a and b is a ‘twin* 
showing double structure. 
Fig. 6. a-e. Hemitetracotyl B. Diagrams illustrating double structure of ‘twin 5 seedling. 
their adjacent sides. Later still the contiguous portions of the endodermal 
layers disappeared, so that the adjacent phloem groups came into contact 
with one another, and became rather reduced in size. No further stage was 
shown in the seedling (Fig. 6, e). 
Seedling C, In this instance the seedling possessed two normal 
