xviii RESPIRATION 



CHAPTER XIV. GENERAL CONCLUSIONS . . .382 



The breathing and circulation are so regulated as to keep the diffusion pres- 

 sures of oxygen, and of hydrogen and hydroxyl ions, in the tissues normal, 382. 

 Breathing and circulation are responses to tissue activity, and do not pri- 

 marily determine it, 383. Claude Bernard and the regulation of internal en- 

 vironment, 383. Diffusion pressures and Bernard's "conditions of life/'sSs. 

 Diffusion pressure of water on the same footing as that of other blood constitu- 

 ents, 384. The blood constituents are in continuous active relation with the 

 living tissues, 385. Comparison of living tissue elements with dissociable 

 chemical molecules, 386. Conception of the living body as the seat of a system 

 of mutually dependent reversible reactions, 386. Defects of the mechanistic 

 and "hormone" theories of physiological inter-connection, 387. The dividing 

 line between biology and the physical sciences, 388. The fundamental con- 

 ception of biology, and the real work of the biological sciences, 389. This 

 work illustrated by the investigations detailed in previous chapters, 389. 

 Real nature of organic identity, 390. The existence of active maintenance of 

 organic identity is the foundation of medicine and surgery, as well as of physiolo- 

 gy and morphology, 391. Examination of the argument that the physical con- 

 ception of Nature is truer and more scientific than the biological, 392. The 

 previous question which is fatal to the physical conception, 394. Physical 

 reality a superficial sensuous appearance, 394. In describing biological phe- 

 nomena and putting her questions to Nature, biology must use her own working 

 hypothesis and not those of the physical sciences, 394. Nature as seen by the 

 biologist, 396. Supposed evolution from "inorganic" conditions, 396. Indi- 

 vidual life and life in association, 396. It is impossible to describe or define 

 conscious activity in either physical or biological terms, 397. Neither the 

 physical nor biological interpretation of Nature is, in the last resort, more than 

 a practical makeshift, 398. The rightful practical sphere of physiology does not 

 include distinctively conscious activity, 399. 



APPENDIX ......... 400 



A. Determination of oxygen capacity of blood haemoglobin by ferricyanide, 400. 

 B. Determination of oxygen capacity of blood haemoglobin by haemoglobin- 

 ometer, 404. C. Determination of oxygen and carbon dioxide in blood by ferri- 

 cyanide and acid, 407. D. Colorimetric determination of percentage saturation 

 of haemoglobin with CO, 418. E. Determination of blood volume in man 

 during life by CO, 424. 



