18 



K. G. HOSKmS 



that such injections often materially impede sympathetic function. In 

 some cases well marked block of sympathetic conduction was demonstrated. 

 This observation, which was confirmed many times both in normal animals 

 and those deprived of their suprarenals, seems to disprove the alternative 

 theory that epinephrin normally facilitates sympathetic function. 



So much for experiments of negative tenor. Boothby has recently 

 reported that as little as 0.5 milligram of epinephrin administered hypo- 

 dermatically may evoke a very marked augmentation of basal metabolism 

 in an adult human being. The effect persists for a matter of hours. At 

 no time under the conditions of the experiment could more than an almost 

 infinitesimal amount of the epinephrin injected be present in the blood 

 stream a quantity much less than that employed in classic pharma- 

 cologic experiments. The sum total of available present-day evidence 

 seems to indicate that epinephrin, in the very small quantities which are 

 probably not transcended under normal conditions, influences in some way 

 the metabolic processes leading to the acceleration of the oxidation reac- 

 tions directly. A variant of this assumption has been developed at length 

 by Sajous in his "respiration theory" of suprarenal function. This writer 

 believes that epinephrin plays a significant role in the taking up of oxygen 

 from the lungs and facilitates its use by the tissues. Further data on the sig- 

 nificance of epinephrin in relation to body function are included in the 

 chapter on "The Pharmacology of the Suprarenals." 



In case of hypophyseal extracts, many of the pharmacodynamic effects, 

 at least, are duo to stimulation of the smooth muscle throughout the body, 

 irrespective of its innervation. In many organs the effects are similar 

 to those of epinephrin, as for example, in the heart. In case of the intes- 

 tine, however, whereas epinephrin causes inhibition of peristalsis hypoph- 

 yseal extracts give predominantly a stimulating effect. That such ex- 

 tracts, however, exert their influence through the nervous system is 

 believed by some observers. Further details will be found in the chapter 

 on "The Pharmacology of the Hypophysis." 



The thyroid hormone seems to have a twofold effect, both catalyzing 

 the metabolism of effector cells directly and augmenting the irritability 

 of the nervous system. This augmenting effect is particularly well seen 

 in the sympathetic system. It is upon the sensitization of the sympathetic 

 system that the well-known "Goetsch test" for "hyperthyroidism" is based. 

 The topic is -further discussed in the chapter on "Tests for Thyroid 

 Disorders." 



In addition to the endocrin products above mentioned, which per- 

 ceptibly influence various functions within a relatively short time after 

 their administration, there are others, the morphogenetic substances, or 

 harmozones of Gley, which manifest their effects only upon the processes 

 <>f growth and development. The thyroid secretion, in addition to its 



