OBSERVATIONS 
ON THE ANATOMY, PHYSIOLOGY AND DEGENERATIONS OF THE 
NERVOUS SYSTEM OF THE BIRD* 
By RUBERT BOYCE, M.B., Professor of Pathology in University College Liverpool 
AND 
W. B. WARRINGTON, M.D., M.R.C.P., Demonstrator of Pathology and 
Assistant Physician to the Hospital for Diseases of the Chest, Lh erpool 
Communicated by Professor Sherrington 
INTRODUCTION 
This research was originally undertaken as a continuation of the studies on the pyramidal 
system made by one of us in Professor Horsley's Laboratory in 1894. This early led to the 
discovery of the fact, which was demonstrated at the time, that in birds the pyramidal system, as 
such, does not exist, and that after complete removal of one hemisphere the resulting degeneration 
in no case extends lower than the mesencephalon. 
All workers, with the exception of SANDMEYER,t are now agreed upon this point. 
In this communication we wish to give a general account of the nervous tracts in the bird, 
and to consider their functional significance. 
Our observations have been made exclusively upon the fowl and pigeon, the anatomy of 
which does not differ, except in insignificant points. 
Complete series of sections have been cut in the transverse, sagittal, and horizontal planes, 
and stained by Weigert's method or the acid haematoxylin stain of Schafer. The sections in 
the horizontal plane appear to us to be especially valuable in completing the information derived 
from those in transverse and sagittal section. 
Various parts of the central nervous system have been injured, and the resulting 
degenerations in the nervous system followed by means of the Marchi method of staining. The 
bird is a favourable subject for such operative interference ; a very slight amount of anaesthetic is 
sufficient, and recovery is almost invariable. Strict antiseptic precautions are not necessary, the 
chief obstacle to a successful operation is the large amount of haemorrhage which takes place 
should a sinus be injured. If such an accident occurs the use of a soft wax is generally sufficient 
to arrest the haemorrhage. 
* Reprinted from the 'Transactions of the Royal Society,' vol. 191, 1899. Part of the expenses of this research were 
defrayed by the Scientific Grants Committee of the British Medical Association. 
■f Sandmeyer, 'Zeits. f. Biologie,' vol. 10. 
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