FUNDAMENTAL PLAN OF VERTEBRATE BRAIN 465 
of the brain cannot adequately be considered by itself. The 
problem of the development of the brain is also that of the head 
and the primitive plan of the brain plate, and the growth changes 
that transform it into the vesicular brain must be in full harmony 
with the facts of development for other cranial structures. 
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Hi 
Figs. land2 Schemas to illustrate the interpretations of Schulte and Tilney (A), 
His (B), Johnston (C), and Kingsbury (D), of the fundamental plan of the brain 
and brain plate, respectively, in terms of primary motor and sensory zones. A, 
alar plate; B, basal plate; F, floor plate; J, primitive infundibulum; 1, mam- 
millary recess; NV, notochord; O, preoptic recess; R, roof plate. 
