384 



Mr. D. T. Harris. 



45. Bordet and Delange, ' Ann. Instit. Pasteur,' vol. 26, p. 669 (1912). 



46. Fano, ' Du Bois Reymond's Arch. f. Physiol.,' 1881, p. 277. 



47. Mellanby, ' Jour. Physiol.,' vol. 38, p. 502 (1909). 



48. Mills, ' Jour. Biol. Chem.,' vol. 46, p. 191 (1921). 



49. Halliburton and Pickering, 'Jour. Physiol.,' vol. 18, p. 293 (1895). 



50. Pickering, ' Compt. Eend. Acad. Sci.,' vol. 120, p. 1345 (1895) ; « Boy. Soc. Proc, 



vol. 60, p. 337 (1896-7). 



51. Le Chatelier, ' Becherches sur les equilibres chimiques,' Paris, 1888. 



52. Delezenne, 'Compt. Bend. Soc. Biol.,' vol. 5, p. 354 (1898). 



53. Nolf, ' Arch. Internat. de Physiol.,' vol. 9, p. 407 (1910). 



54. Pavloff, ' Du Bois Reymond's Arch. f. Physiol.,' 1887, p. 452. 



55. Doyon, 'Compt. Rend. Soc. Biol.,' vol. 68, p. 752 (1910). 



Active Hyperemia. 

 By D. T. Harris (Beit Memorial Research Fellow). 



(Communicated by Prof. W. M. Bayliss, F.B.S. Received January 20, 1922.) 



(From the Institute of Physiology, University College, London.) 



CONTENTS. 



PAGE 



1. Introduction 384 



2. Methods 387 



3. Vaso-Constrictor Nerves 389 



4. Vaso-Dilator Nerves 390 



5. Metabolites 393 



6. Functional Hypersemia : 398 



7. Control of Body Temperature 403 



8. Conclusions 404 



1. Introduction. 



So conflicting are the statements made by physiologists and pathologists 

 alike, relating to the mechanism by which " an increased afflux of blood to a 

 part " is brought about, that it was felt desirable to investigate this important 

 phenomenon. Let us first consider the present state of knowledge regarding 

 the possible factors involved. 



(i) Vaso-constrictor Nerves (neuro-paralytic hyperemia). — The existence of 

 vaso-constrictor nerves was first demonstrated in the cervical sympathetic by 

 Claude Bernard (1852), and independently by Brown-Sequard. The inter- 

 ruption of the normal stream of impulses from the vaso-motor centres ' along 

 these nerves gives rise to a " neuro-paralytic hyperemia," such as is met with 

 surgically in wounds of the neck, or in lesions of the spinal cord. During the 



