730 
Lee. — Observations on the 
During the greater part of the transition, the four vascular groups in the 
hypocotyl are equal in size and similar in configuration, and it is impossible 
structurally to distinguish between the intercotyledonary strands and those 
in the plane of the cotyledon. The phloem is extremely small in amount, 
and at no point can internal phloem be recognized with certainty — an 
observation which emphasizes the late appearance of this tissue noticed by 
other observers. 
Finally/the protoxylem in each case becomes definitely external, and 
the metaxylem groups fuse ; the xylem masses move towards the centre, 
the corresponding phloem groups meet and fuse, and a tetrarch root is 
