5/0 A MANUAL OF PHYSIOLOGY 



to accumulate in the tissues, showing that the destruction of protein 

 was increased a conclusion which seemed to derive support from 

 the wasting of the animal. It has since been shown that an in- 

 creased output of nitrogen is not of constant occurrence, and only 

 takes place under the same conditions as in starvation (p. 531)". 



FIG. 192. EFFECT OF BONE-MARROW ON BLOOD-PRESSURE. INTRAVENOUS 

 INJECTION OF SALINE EXTRACT. VAGI INTACT. 



The uppermost line is a signal trace showing the time and length of injection. 

 Below this is the record of the respiratory movements, and lowest the blood- 

 pressure tracing. To be read from left to right. 



As a matter of fact, the animals waste and die within a few days or 

 weeks largely because they refuse to eat. Polyuria (increase of 

 urine beyond the normal) does not necessarily occur. It is well 

 known that when only one kidney is extirpated the other hyper- 

 trophies, and no ill-effects ensue. 



The statement that extracts of the kidney when injected into the 



^ i veins of an animal cause a rise 



of arterial blood-pressure, es- 

 sentially through direct action 

 on the peripheral vaso-motor 

 mechanism, is of considerable 

 nAi*i^l\ interest, for it may possibly 



|M|j|ff|' V have some bearing on the rise 



W jH^MMMH ^ P ressure an d consequent 



*\ Ji^ hypertrophy of the heart asso- 



\ Jf ciated with certain renal dis- 



\k, ^^|JF eases. But there is not as yet 



^Jtojjj^ sufficient evidence that the 



hypothetical pressor substance, 



FIG. 193. INJECTION OF EXTRACT OF to which the name ' renin ' has 



BONE-MARROW WITH THE VAGI CUT. been given, in any sense re- 



To be read from left to right. presents an internal secretion 



of the kidney. The pressor 



substance (so-called " urohypertensine ") which can be extracted by 

 ether from normal human urine (Abelous) is probably only excreted 

 by the kidney, and perhaps arises from the putrefaction of proteins 

 in the intestine. For it has been shown that in the putrefaction 

 of (horse-) meat bases are formed which, when injected intravenously, 

 cause a rise of blood-pressure. The most active of these is a body 



