911.] IN RELATION TO THE EMOTIONS. 87 



tremors decrease, there is a rapid increase in the body weight, and 

 the patient gradually resumes his normal state. On the other hand, 

 if to a normal individual extract of the thyroid gland is administered 

 in excessive dosage over a period of time, there will develop ner- 

 vousness, palpitation of the heart, sweating, loss of weight, slight 

 protrusion of the eyes, indigestion; in short there will be produced, 

 artificially, most of the phenomena of Graves' Disease and of the 

 strong emotions. On discontinuing the administration of the thy- 

 roid extract these phenomena may disappear. On the other hand, 

 when there is too little or no thyroid gland the individual becomes 

 dull and stupid and emotionless, though he may be irritable ; but if a 

 sufficient amount of thyroid extract is given such a patient he may be 

 brought up to the normal again. 



Hence, we see that the phenomena of the emotions may be, 

 within certain limits, increased, or may be diminished, or abolished 

 by increasing, diminishing, or totally excluding the secretion of the 

 thyroid gland. 



Graves' Disease may be increased by giving thyroid extract, and 

 by fear. It may be diminished by removing a part of the gland, or 

 by tying the blood and nerve supply, or by complete rest. Finally in 

 Graves' Disease there is at some stage an increase in the size and in 

 the number of the secreting cells. These facts relating to the nor- 

 mal and the pathological supply of thyroid secretion point to this 

 gland as one of the sources of the energizing substance or substances 

 for the execution of the motor phenomena of animals as well as the 

 expression of their emotions. 



Anger is, of course, of similar origin and is an integration and 

 stimulation of the motor mechanism and its accessories. Animals 

 having no natural weapons for attack ■ experience no emotion or 

 anger, and the animals that have weapons for attack express anger 

 principally by energizing the muscles used in attack. Although the 

 efficiency of the hands of man has largely supplanted the use of tlie 

 teeth, he still shows his teeth in anger and so gives support to the 

 remote ancestral origin of this emotion and the great persistence of 

 phylogenetic association. On this conception we can understand 

 why it is that a patient consumed by worry — which to me signifies 



