DEVELOPMENT OF REFLEX MECHANISMS 79 
little farther dorsally in the acustico-lateral area. Its dendrites 
may reach the root zone of the lateral line root of the vagus, of the 
VIII root, of the spinal V tract, and even farther ventrally into 
the tegmentum, where it may receive collaterals from the spino- 
bulbar and spino-tectal paths. The axone of this neurone enters 
the lateral lemniscus (lm.) for connections with the midbrain 
and thalamus. 
The relations of these nerve centers in adult Amblystoma 
have been only superficially studied. There is undoubtedly 
some advance in specialization over the larval condition, but 
apparently no fundamental changes in reflex pattern. Further 
research is needed to clarify the details of this situation in the 
adult. 
REFERENCE LETTERS 
for figures 8, 9 and 10 
a.ac., area acustico-lateralis r.VII.l.l.m., radix lateralis facialis 
c.cb., corpus cerebelli 
com.cb., commissura cerebelli (medul- 
lated component) 
f.l.m., fasciculus longitudinalis medi- 
alis 
f.l.m.VI., tract from area acustico- 
lateralis to VI nucleus 
f.sol., fasciculus solitarius 
gen.cul.X., general cutaneous root of 
vagus 
1.U.X., radix lateralis vagi 
lm., bulbar lemniscus 
acustico-lateralis) 
lob.vis., lobus visceralis 
n.IV., nervus trochlearis 
N.IX., nervus glossopharyngeus 
n.sp.1., first spinal nerve 
nuc.[X .m., nucleus motorius IX 
nuc.VI.m., nucleus motorius VI 
n.V., nervus trigeminus 
n.VI., nervus abducens 
n.VIII., nervus acusticus 
r.IX.mot., radix motorius [X 
r.V., sensory root of the V nerve 
r.VII.L.1., radix lateralis facialis 
r.VII.1.l.d., radix lateralis facialis 
dorsalis 
(from area 
medius 
r.VII.1.l.v., radix lateralis facialis ven- 
tralis 
r.VII.v.s., visceral sensory root of the 
facialis 
r.VIII., radix nervi acustici 
r.VIII.d., radix dorsalis acustici 
r.VIII.v., radix ventralis acustici 
r.X.1.l.d., radix lateralis vagi dorsalis 
r.X.l.l.v., radix lateralis vagi ven- 
tralis : 
r.X.2 lo r.X.7, second to seventh roots 
of the vagus 
tr.a., dorsal longitudinal tract of arex 
acustica 
ir.b., ventral longitudinal tract of 
area acustica 
ir.b.sp., tractus bulbo-spinalis 
ir.b.t., tractus bulbo-tectalis 
tr.sp.t., tractus spino-tectalis 
ir.t.b., tractus tecto-bulbaris 
ir.v.a., tractus visceralis ascendens 
(secondary gustatory tract) 
Visc.sens.X., visceral sensory root of 
vagus 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL 25, No. 1 
