THE DUCTLESS GLANDS 1323 



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 Isevorotatory 

 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 laevorotatory. Adrenalin is active 

 in excessively minute doses, injection of one four-hundredth of a milli- 

 gramme per kilo body weight sufficing to evoke a definite rise of 

 blood pressure. On injecting it into the circulation there is imme- 

 diately 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 adrenalin 

 evokes a huge rise of pressure which may amount to 300 mm. Hg. It 

 may indeed be so great 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, how- 

 ever, limited to the blood-vessels. It has been shown by Langley and 

 by Elliott that adrenalin injected into the circulation arouses every 

 activity which can be normally excited by stimulation of the sympa- 

 thetic system. A list of the actions of adrenalin 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 augment or and 

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

 even against the enormously increased resistance offered by the con- 

 stricted arterioles. Whereas a rise of blood pressure generally causes 

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

 of adrenalin 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 adrenalin has no constrictor influence, which is 

 in accordance with the results obtained by stimulating the sympa- 

 thetic system. 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 

 adrenalin to the perfused blood, while others have been unable to 

 obtain any positive results in this direction. In the abdomen intra- 

 venous injection of adrenalin causes complete relaxation of the muscu- 

 lature of the stomach, small and large intestines, but causes contrac- 

 tion of the ileocolic sphincter. On the bladder its effect varies 

 according to the animal studied, but in every case is identical with that 



