THE EPIBRANCHIAL GANGLIA OF LEPIDOSTEUS 3 
of the first true gill and the visceral portion of the ganglion is 
detached from the lateralis portion. Herrick (07) found only 
special visceral or gustatory fibers arising from the visceral gang- 
lion so that, since the visceral portion of the ganglion is exclu- 
sively placodal in origin, we are warranted in concluding that 
the epibranchial placodes give rise to those ganglionic cells from 
which gustatory fibers arise. This conclusion is strengthened by 
a number of facts that need not be repeated here. It does not 
seem an unwarranted conclusion that this is the function of the 
epibranchial placodes in all classes of vertebrates, although its 
demonstration in the higher vertebrates will always be a differ- 
cult undertaking, owing to the fact that the relations of the pla- 
code to the general visceral ganglion rarely seem to be so diagram- 
matic as in Ameiurus and that it is extemely difficult to secure 
a series of embryos of the higher vertebrates in stages sufficiently 
close to follow all the changes, since these series must in the 
lower forms, at least, be as close as four hours. 
These facts emphasize the necessity of clearing the problem 
up as far as possible among the lower vertebrates, where series 
can be secured at sufficiently close intervals and where we should 
expect to find simpler relations owing to the generalized condi- 
tions. of the peripheral nervous system. Of equal importance 
with the two facts just mentioned, however, is that of the hyper- 
trophy of some of the components of the peripheral nerves, espec- 
ially among the Ichthyopsida. This is probably the reason for 
the diagrammatic simplicity of the special visceral system of 
Amelurus. 
While Lepidosteus was taken up primarily because it is a 
generalized type, it appears that there is a beautiful example of 
hypertrophy in the case of the visceral portion of the VII ganglion 
as compared with the same ganglia in the IX and X. This is 
probably associated with the elongation of the head and the 
consequent increase in the area supplied by the VII nerve. 
One of the principal difficulties encountered in the study of 
the placodes in Lepidosteus arises from the fact that the endo- 
dermal evagination from the pharynx is long anterio-posteriorly, 
