44 THE GLANDS REGULATING PERSONALITY 



supplying the highway for travel and transmission of the post, 

 the post consisting of the chemical substances secreted by the 

 glands. To be sure, the doctrine was only an inference, though 

 well-founded, of which the direct experimental proof was not to 

 be obtained until the researches of Bayliss and Starling. Yet to 

 Brown-Sequard belongs the immortal credit, if not of the origina- 

 tor, at any rate of the resurrector of the idea of using gland 

 extracts to influence the body. The unwarranted hopes aroused 

 by his enthusiastic reports of rejuvenating miracles have long 

 since been dissipated. Moreover, they smeared the whole subject 

 with a disrepute which clings to certain narrow and unreasonable 

 minds to this day. But as every physiologist since has acknowl- 

 edged, he was and remains the great path-breaker in the conquest 

 of the internal secretions. 



The Hormones 



The problem of the internal secretions was now attacked from 

 another angle. A great Russian physiologist, Pawlow, called 

 attention to the fact that the introduction of a dilute mineral 

 acid, such as the hydrochloric acid, normally a constituent of 

 the stomach digestive fluid, into the upper part of the intestine, 

 provoked a secretion of the pancreas, which is so important for 

 intestinal digestion. He explained the phenomenon as a reflex, 

 a matter of the nerves going from the intestine to the pancreas. 



His pupil, Popielski, threw doubt upon so easy an explanation, 

 by proving that the same reaction could be elicited even after all 

 the nerve connections between the gut and the spinal cord were 

 severed. If the relation was a reflex, it would have to be classed 

 now as one of those local nerve circuits, which are pretty common 

 among the viscera, a local call and reply as it were, without 

 mediation of the great long distance trunk lines in the spinal 

 cord and the medulla oblongata. 



The work of Bayliss and Starling, two English physiologists, 

 was commenced then to test the hypothesis. They soon found 

 that the experiment could be so devised as to exclude any influ- 

 ence whatever on the part of the nervous tissues, and yet result 

 positively. Thus, if a loop of intestine was so prepared as to be 

 attached to the rest of the body only by means of its blood ves- 

 sels, all the nerves being cut, putting some acid into it was still 

 followed by a flow of pancreatic juice, no less marked than when 

 none of the parts about the piece of gut had been disturbed. It 



