470 LANDACRE AND McLELLAN 
ganglion a sympathetic cord extends forward and enters the X 
complex, from which a second sympathetic nerve runs forward to 
unite with the trigemino-facial complex. The connection between 
the glossopharyngo-vagal ganglion, the so-called jugular of the 
adult, and the trigemino-facial is intracranial. In the 10 mm. 
embryo there are sympathetic ganglia on both the first and second 
spinal nerves in the usual positions. The sympathetic ganglion on 
the first spinal nerve is quite small, as is also the sensory ganglion 
of this nerve. The sympathetic ganglion on the second spinal 
nerve is, on the contrary, quite large. This, as stated above, 
is the first sympathetic of the adult. A careful examination of 
our whole series of embryos reveals no sympathetic ganglion in 
the region of the X. In fact, up to our latest stage and even ina 
35 mm. embryo it is not possible to follow the sympathetic nerve 
from the second sympathetic into the X as a continuous cord and 
we have been unable to follow with certainty the intracranial con- 
nection between X + IX and V + VII ganglia. 
These facts indicate that the sympathetic ganglion and cords 
are in & very immature condition in a 10 mm. embryo and even in 
a 35 mm. embryo are difficult to follow in detail. 
In a 10 mm. embryo the first spinal ‘ganglion is situated 22 
sections posterior to the posterior end of lateralis X and the 
second spinal ganglion is 48 sections posterior to this point, so 
that the first sympathetic ganglion of a 10 mm. embryo which 
becomes the first ganglion sympatheticus cervicale is back of the 
posterior end of lateralis X, a distance equal to the total anterior 
posterior length of IX + X. The change from this condition 
to that figured by Strong, if he has correctly located this ganglion, 
can only be accounted for by the shifting backwards of the [IX + 
X complex by the enlargement of the auditory vesicle. 
THE VENTRAL LATERALIS X 
This ganglion (figs. 1, 2, 6, 10, V.L.X.) occupies, as indicated 
above, the lateral position in the most distal and ventral division 
of the second group of ganglia. It is elongated dorso-ventrally ; 
at its dorsal border it is in contact, particularly in later stages, 
from 10 mm. on, with the ventral end of dorsal lateralis X and 
