PLATE 10 
Fig. 50 from a 11.5 mm. embryo is taken through the ‘comma’ stage of the pla- 
code of the first branchial ganglion of X and shows the relation assumed by the 
placodal and general visceral cells in a ganglion where they are approximately 
equal in number. 
Fig. 51 from a 10 mm. embryo shows an early stage of the epibranchial placode 
of the second branchial ganglion of the X at a stage where it is still attached to 
the ectoderm. 
Fig. 52 from a 10.9 mm. embryo shows a late stage in the second epibranchial 
ganglion of X. The incorporation of placodal cells is not complete, there being 
a ventro-lateral spur of placodal cells and, contrary to the usual rule, the placodal 
cells lie chiefly on the lateral portion of the general visceral ganglion. 
Fig. 53 from a 10.9 mm. embryo shows an early stage before detachment of the 
epibranchial placode of the third branchial ganglion. 
Fig. 54 from a 11.5 mm. shows the process of incorporation of the third epibran- 
chial placode into the ganglion of the X. The lateral spur is still present. 
Fig. 55 from a 12.9 mm. embryo shows. an early stage in the formation of the 
fourth epibranchial placode of the X. The general visceral cells are so numerous 
that the relation seems to be one of contact only but later series show that there is 
an actual contribution by the placode of the ganglion. 
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