BILATERAIv VAGOTOMY OF FROG 
211 
destined for the heart and stomach. In unilateral section only 
the right or left vagus nerve was cut. In the case of bi- 
lateral vagotomy, both vagi were always sectioned at one opera- 
tion and the skin incisions closed with four sutures. After 
recovery of the animals, direct observations were made on the 
visible changes in the contour of the flanks and the external re- 
spiratory movements and compared with that of the normal or 
control animal. 
The animals were kept under observation for periods of 
several weeks and even months in many cases. During this time 
they were kept in a large vivarium which was divided into small 
compartments in which the animals were kept in pairs (control 
and vagotomized). This was provided with running water and 
the animals in all the later experiments were fed on caterpillars 
and earthworms in order to keep them in first class condition, for 
any depression in the animals might defeat the object of the ex- 
periment. To further control any possibility of depression result- 
ing from the confinement of the animals, the vagi were sectioned 
in many of the control animals, five to eight weeks after the 
cutting of the nerves in the first animal but these latter or con- 
trol animals always reacted in exactly the same manner as the 
former. Finally, all the animals at the close of the respective ex- 
periments were autopsied and the condition of the lungs and other 
visceral organs observed. 
Since the results of this study have been published in full 
in the American Journal of Physiology (November, 1921), Vol. 
LVIII, No. 1, it is necessary here only to give a resume of some 
of the more important conclusions. 
Bilateral vagotomy in the frog (Rana pipiens) destroys the 
inhibitory control over the peripheral lung automatism leaving it 
free to exert its full influence on the lungs without any check, 
hence the lungs contract and pass into a state of hypertonus or 
lung tetanus to such a degree as to nullify their function. The 
normal contour of the flanks in these animals disappears and the 
body line becomes straight or even curved in. 
In unilateral section of the vago-sympathetic nerve there is loss 
of the inhibitory control over the peripheral lung automatism on 
the side of the section only, the opposite lung being unaffected, 
thus showing that the nerve action is unilateral. 
In both unilateral and bilateral section of the vago-sympathetic 
nerves there is a gradual physiological readjustment of the peri- 
pheral lung motor mechanism which usually starts from 12 to 
