460 L. S. STONE 



ficial cells of the ectoderm, for the deeper-lying sense organs in 

 the intruded area are undisturbed. However, this is a subject 

 for further investigation. 



A specimen killed eight days after operation shows a complete 

 absence of the ophthalmic ganglion and the ophthalmicus pro- 

 fundus V nerve (figs. 40 a and b). The size of the ophthalmic 

 ganglion of the normal side of this indi\ddual is very large (fig. 41), 

 and a comparison between it and the region of the root of the V 

 on the operated side (fig. 42) renders a striking picture. The 

 crest cells concerned in the formation of the visceral skeleton 

 along the region of the mandibular arch are approximately nor- 

 mal in amount. This condition indicates that if any of the crest 

 cells had been disturbed there has been a regeneration, and 

 ample opportunity has been offered to contribute to the forma- 

 tion of the ganglion if such were their function. This individual 

 also shows a diminution in the size of the gasserian ganglion as 

 illustrated by figure 40 a. Another individual killed nineteen 

 days after a similar operation at stage 23 shows no ophthalmicus 

 profundus V nerve and the small ganglionic mass which does 

 appear is apparently concerned only with the gasserian portion 

 (fig. 43). 



An individual which had been operated upon at stage 26 shows 

 nine days later a very small ganglion represented by possibly 

 no more than ten cells (fig. 44). The only representative of the 

 ophthalmicus profundus V nerve appears in but one section and 

 extends anteriorly as a slender nerve fiber. During stage 26 

 cells are being given off from the ophthalmic placode, and it is 

 quite possible that a few of the placodal cells remained in the 

 wound and later gave rise to the remnant of the ganglion which 

 appears in this section. The gasserian ganglion is also smaller 

 in this individual than is the normal ganglion of the left side. 



An individual which was operated upon at stage 23 shows a 

 small ophthalmic ganglion in an abnormal position (figs. 45 a 

 and b). This ganglionic mass lies median to the eye and some- 

 what dorsal to the optic nerve. It is connected to the brain by 

 a slender group of fibers which pass back through the gasserian 

 ganglion into the brain. At the lower anterior portion of this 



