116 PSYCHOBIOLOGY 



tion of the digestive juices and also the muscular activity of the alimentary 

 canal. It has long been known that certain strong emotions, especially 

 fear and rage, are accompanied or followed by important changes in the 

 digestive process, and the study of adrenalin is now revealing a part of 

 the mechanism of the occurrences. On the physiological side, the research 

 of Cannon and his pupils opens up what is probably the most important 

 line of attack on the problems of the emotions. 



The foregoing sketch of the functions of the ductless glands should be 

 taken as a statement of probabilities. There is serious conflict of opinion 

 and conflict of apparent experimental results concerning these organs. At 

 the present time an enormous amount of work is being done in this field 

 by the pharmacologists, and the results of their researches will some time be 

 of great value to psychology. 



The psychological importance of the ductless glands does not lie simply 

 in the fact that they are essential to the growth, nutrition and irritability 

 of the muscular, glandular and nervous tissues, but in the connection which 

 seems to exist between internal secretion and affective content of conscious- 

 ness. Although we have as yet no data indicating clearly whether the 

 hormones have a neural stimulatory value, exciting end-organs of affer- 

 ent fibers in the viscera, or whether the consciousness factor is associated 

 merely with the nerve reflexes which terminate in the activation of the 

 glands, it is probable that the physiological basis of affective content will 

 be found to be partly in some phase or phases of secretion. 



The physiological basis of feeling is doubtless wider than internal secre- 

 tion. On the one hand the nerve fibers activating the duct-glands are at 

 least as important as those activating the ductless glands. On the other 

 hand, if there are nerve receptors which are stimulated by hormones there 

 are also probably receptors stimulated by other bodily products, such as 

 carbon dioxid, lactic acid, and glycogen. Moreover, the activity of smooth 

 muscle (aside from the smooth muscle involved in certain of the glands) 

 probably plays some part in the physiological conditioning of affective 

 contents and consciousness. 



REFERENCES ON GLANDS. 

 I. ON GLANDS IN GENERAL AND DUCT GLANDS IN PARTICULAR. 



Luciani, Human Physiology. (Translated by Welby.) Vol. III. (Internal secre- 

 tion, digestion, and excretion.) 



Birmingham, The Digestive System. Cunningham's Anatomy. In particular, § 

 Glands. 



Howden, The Organs of Sense and the Integument. Cunningham's Anatomy, § 

 The Skin. 



