ON THE ACTION OF NITRITE OF AMYL ON 

 THE CIRCULATION [AND ON ACTIVE DI- 

 LATATION AND CONTRACTION OF ARTE- 

 RIOLES INDEPENDENTLY OF NERVE- 

 CENTRES].* 



(From the Journal of Anatomy and Physiology, vol. v, 1871, pp. 92 to 101.) 



The property of causing flushing of the face and throbbing 

 of the carotids, which nitrite of amyl possesses, was first 

 observed by Guthrie in 1859, but no further notice of it was 

 taken till Dr. Eichardson, in 1866, again drew attention to it. 

 His experiments led him to conclude that it paralysed the 

 nerves from the periphery to the centre, lessened the con- 

 tractility of the muscles, and dilated the capillaries in the 

 web of the frog. They were shortly afterwards repeated by 

 Drs. Gamgee and Rutherford, who, however, found no action on 

 the nerves, either sensory or motor, and rarely any on the 

 capillaries of the frog. In some other experiments, also un- 

 published, but whose results they have kindly communicated to 

 me, they found that the sphygmographic tracing of the radial 

 pulse underwent a remarkable change, the waves becoming 

 much more frequent, and their ascent, but especially descent, 

 much more rapid ; and the pulse-rate and pressure in a mano- 



* Tlie chief research on which I was engaged in Profe-sor Ludwig's labora- 

 tory during the summer of 1869 and winter of 1869-70 was that relating to the 

 local dilatation and contraction of arterioles independently of nerve-centres. 

 This was the research which Professor Ludwig had suggested and on which he 

 worked with me, while that on nitrite of amyl was only carried on at those 

 times when Professor Ludwig was engaged with other students. As time did 

 not allow me to finish the research on the arterioles, that on nitrite of amyl 

 was published and. only a brief abstract given of the results obtained during 

 the researcl) on the arterioles, both Professor Ludwig and I hoping that cir- 

 cumstances might allow me to return to his laboratory and finish it. This was 

 unfortunately not the case, and lie continued to work at the subject with Hafiz, 

 Lepine, A. Mosso, Von Frey, and Gaskell, 



