366 THE INFLUENCE OF THE ORGANS ON ONE ANOTHER 



set up by the injection of the blood of one animal deprived of its adrenals 

 into another animal operated on in the same way, appear to speak rather 

 definitely for the former supposition. Even if this were correct, however, 

 the physiological purpose of the adrenals would not be wholly explained there- 

 by, for injection of adrenal extract or of blood from the adrenal vein (Cy- 

 bulski) into animals which have lost their adrenal bodies produces a marked 

 improvement in the symptoms for some time, and has an unmistakable effect 

 on perfectly normal animals. The conclusion which seems to be inevitable 

 is that the adrenals give off to the blood one or more specifically active 

 substances. 



These substances are dialyzable; soluble in water, dilute alcohol and in 

 glycerin, but insoluble in absolute alcohol and ether ; withstand drying at 110 C. 

 and boiling, if not too prolonged. They are destroyed by alkalies, but not by 

 acids. Numerous attempts have been made to isolate and identify this sub- 

 stance. According to v. Fiirth, it is related to the pyridin series and contains 

 a ring nucleus with two hydroxyl groups in the ortho position (adrenalin). It 

 has an alkaline reaction and forms salts with the acids. Its empirical formula, 

 according to Takamine, is C 10 H 15 NO 3 , according to Abel C 10 H 13 NO 3 . + i H 2 O. 

 The percentage of this substance in the adrenals is said to be about 0.1-0.17 

 per cent. 



If the extract be injected directly into a vein, it acts powerfully in very 

 small quantities. Thus Takamine obtained a distinct rise of pressure by inject- 

 ing 0.0000013 g. of adrenalin. The chief effect of such an injection of this 

 extract is a sudden rise of blood pressure. This is due in part to an augmented 

 heart action which can be demonstrated also on an excised heart or heart muscle, 

 and in part to a powerful contraction of the smaller arteries caused by a direct 

 action of the extract on the musculature of the vessels. According to Cyon, the 

 vasomotor center in the medulla and the cardiac inhibitory center are excited. 

 The slowing of the heart beats observed by many authors, which do not appear 

 after section of the vagi (according to most authors), is said to be a direct effect 

 of the injection and the result of a sudden increase of intracranial pressure. 



Most of the effects of injection of adrenalin last only a few minutes, and 

 then gradually disappear. This temporary character might be due either to a 

 transformation of the adrenalin taking place in the blood stream, or to its 

 removal from the vessels. Adrenalin is eliminated in the urine only in very 

 small quantities. 



When injection is made subcutaneously in animals from which the adrenals 

 have been removed, it produces a rise during the premortal fall of temperature, 

 and improves the general bodily condition of the animals. They become more 

 active, the weakness and uncertainty of their movements are diminished and 

 they leap with much more vigor than before. After repeated injections, how- 

 ever, the effect fails, and it is possible to prolong the life of the animal in this 

 way for only about twenty-four hours (Hultgren and O. Andersson). On ad- 

 ministration of very large quantities of adrenalin to normal animals, especially 

 after intravenous injection, profound toxic effects ensue which result fatally. 



With regard to the influence of the nervous system on the formation and 

 secretion of the active substance of the adrenals, Biedel and Dreyer state that 

 stimulation of the splanchnic below the diaphragm produces, quite independ- 

 ently of the alterations in the blood flow, a copious secretion of it into the 

 blood. 



