PLATE 2 
EXPLANATION OF FIGURES 
3 Five-day chick embryo, no. 1. Section through thoracic segment (X 165), 
showing ventral nerve-root (vr) and primordium of sympathetic trunk (sy) in 
absence of spinal ganglion and dorsal nerve-root. 
4 Five-day chick embryo, no. 3. Section through thoracic segment (X 165), 
showing remnant of neural tube with ventral nerve-root (vr) and small primor- 
dium of sympathetic trunk (sy). 
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