THE DUCTLESS GLANDS 1183 



physiological chemists have succeeded not only in determining the consti- 

 tution of adrenaline but also in preparing it synthetically. The constitution 

 of adrenaline is shown by the following formula : 



CH(OH) CH 2 NHCH 3 



Since it possesses an asymmetric carbon atom, a substance of this formula 

 may be either laevo- or dextrorotatory. Both forms, as well as the racemic 

 modification, have been prepared synthetically. The substance which 

 occurs in the suprarenal gland is the laevorotatory modification, and Cushny 

 has shown that it is only this modification which is active, injection of the 

 dextrorotatory compound having only one-twelfth the effect of the laevo- 

 rotatory. Adrenaline is active in excessively minute doses, injection of 

 one four-hundredth of a milligramme per kilo body weight sufficing to evoke 

 a definite rise of blood-pressure. On injecting it into the circulation there is 

 immediately a rise of blood-pressure which, if the vagi are intact, is only 

 moderate in amount, but is accompanied by a marked slowing of the heart. 

 This excitation of the vagus is, however, probably secondary to the rise 

 of blood-pressure and is not due to direct action of the drug on the vagus 

 centre. If the vagi be divided the injection of adrenaline evokes a huge 

 rise of pressure which may amount to 300 mm. Hg. It may indeed be so 

 gre.it that the animal dies from heart-failure or from pulmonary oedema. 

 The rise of pressure is observed even after destruction of the central nervous 

 system. The action is not limited to the blood-vessels. It has been 

 shown by Langley and by Elliott that adrenaline injected into the circu- 

 lation arouses every activity which can be normally excited by stimulation 

 of the sympathetic system. A list of the actions of adrenaline is therefore 

 identical with a list of the chief functions of the sympathetic nervous 

 system. In the head it causes dilatation of the pupil, secretion of saliva, 

 and erection of the hairs. On the heart it has a strong augmentor and 

 accelerator influence, so that the heart beats more effectively as a rule 

 even against the enormously increased resistance offered by the constricted 

 arterioles. Whereas a rise of blood-pressure generally causes increased 

 systolic volume of the heart, we may find after an injection of adrenaline and 

 during the height of the rise of blood-pressure that the heart empties itself 

 more effectively than it did before the injection. On the lung- vessels 

 adrenaline has probably a slight constrictor influence. With regard to the 

 vessels of the brain, we find the same divergence of opinion as in the case of 

 excitation of possible vaso-motor nerves to this organ. Some observers, 

 on perfusing the brain with defibrinated blood, have obtained constriction 

 on adding adrenaline to the perfused blood, while others have been unable to 

 obtain any positive results in this direction. In the abdomen intravenous 

 injection of adrenaline causes complete relaxation of the musculature of 

 the stomach, small and large intestines, but contraction of the ileocolic 

 sphincter. On the bladder its effect varies according to the animal studied, 



