PLATE 6 
Fig. 29 from a 12.4 mm. embryo, is taken from approximately the same position 
in the VII ganglionic complex as fig. 25, which is from a 10.9mm. embryo. There 
are no placodal cells present in this section except the caudally projecting spur. 
This is soon incorporated into the geniculate ganglion. The close resemblance 
histologically between the dorso-lateral and the geniculate, and the distinct 
character of the ventro-lateral which are so noticeable in this figure, can be detec- 
ted in. all earlier stages. 
Fig. 30 is taken from the same embryo (12.4 mm.) as that from which fig. 29 
was taken and lies five sections anterior to fig. 29. Only the anterior tip of the 
ventro-lateral ganglion shows and the dorso-lateral has been omitted on account 
of its size. The placodal ganglion projects somewhat from the ventro-lateral 
surface of the geniculate. 
Fig. 31 shows the same relations in a13.5mm.embryo. The placodal ganglion 
is almost completely incorporated into the geniculate. The distinction shown 
here between unaltered placodal cells and the normal ganglion cells of the geni- 
culate is fairly representative for all later stages in which placodal cells can be 
detected. 
Fig. 32 shows the detail of the epibranchial placode of the VII in a 9.5 mm. 
embryo and illustrates the relation of the placode to the ectoderm above and below 
its point of attachment. This figure corresponds to the middle of the placode 
shown in fig. 33. 
Fig. 33 is a sketch of a wax reconstruction of the epibranchial placode of VII 
and associated structures in the ectoderm and endoderm. The model rests on its 
anterior surface and is seen from the ventral surface. The ectoderm with its 
attached epibranchial placode is detached from the endoderm and that portion 
of the ectoderm lying anterior to the placode. The hyoid gill pocket lies to the 
right and is closely fused with the ectoderm back to the point of origin of the pla- 
code. If the two portions of the model are placed together it will be seen that the 
anterior surface of the epibranchial placode rests upon the posterior surface of 
that portion of the hyoid gill pocket that comes into contact with the ectoderm. 
The length of the embryo from which the model was reconstructed was 9.7 mm. 
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