VARIATION, .OF , THE (SPIRALS NERVES. IN THE 
CAUDAL. REGION |\OR (GE (DOMESTIC 
PIGEON. 
JAMES I. PECK, A.B. 
OnE of the most conspicuous of the variations in the internal 
structure of the common domestic pigeon, is that which affects 
the number of the vertebrze in the caudal region. These ordi- 
narily vary from five to eight between the sacrum and coccyx ; 
and it was the purpose of this work to determine whether the 
pairs of spinal nerves vary in the same ratio, or whether they 
remain constant in number and position of exit from the verte- 
bral canal, without reference to the number of vertebra them- 
selves. 
The methods were first by dissection, and the accuracy of the 
results so gained was then tested upon the same and other 
specimens by cutting sections. Before dissecting, the whole 
caudal region was taken from the bird, the muscles and con- 
nective tissues removed from one side so as to determine accu- 
rately the number of free vertebra, but left upon the other side 
so as to leave all spinal nerves intact. The part was then placed 
for a fortnight or more in an aqueous solution of picric acid 
until the nerves were hardened and the vertebrae somewhat 
decalcified, so that their processes could be cut easily with a 
sharp scalpel; the specimen was then pinned out under water, 
the neural arches cut away, and the cord and pairs of nerves so 
exposed were traced out under a lens with bent needle points. 
A considerable number of birds were dissected in the fresh 
state also, but with less certainty about the last nerves. For 
cutting sections, a much longer decalcification in picric acid was 
required before the centra of the vertebrae would become suf- 
ficiently pliable, and a maceration in a ten per cent solution of 
nitric acid for two or more days was found to be more expedi- 
tious. Borax carmine and hzmatoxylin were used for staining, 
and the material imbedded in paraffine. 
