MELANOPHORES OF THE HORNED TOAD 301 



If adrenin is the hormone responsible for the contraction of the 

 melanophore pigment following noxious stimulation, it should be 

 possible to recognize its presence in the circulation at such a time 

 by its characteristic effects upon other bodily conditions. The 

 action of adrenin upon the heart, blood pressure, alimentary mas- 

 culature, and the iris do not form good criteria of the presence of 

 adrenin in the circulation during emotional states, because in 

 such a small animal as the horned it is very difficult to be sure the 

 effects are not produced through the sympathetic nervous 

 system. 



The presence of adrenin in the circulation, however, causes a 

 change in its sugar content. It has been shown by Paton ('03), 

 Bierry et Gatin-Gruzewska ('05), and others that glucose appears 

 in abnormally large quantities in the blood stream after the 

 injection of adrenin into it. Blum ('01) has discovered that 

 adrenin injections will produce glycosuria, another manifestation 

 of the same action of this hormone. Cannon, Shohl and Wright 

 ('11) found that when cats are excited for even so short a time 

 as one-half hour they exhibit glycosuria. This emotional gly- 

 cosuria is produced by the secretion of adrenin which accompanies 

 emotional excitement. If adrenin occurs in abnormal quantities 

 in the circulation of the horned toad during states of excitement, 

 its presence should be indicated by an increase in the concen- 

 tration of blood sugar. 



The sugar content of the blood of fifteen horned toads was 

 determined by the method of Myers and Bailey ('16). The first 

 series, representing the normal sugar content of the blood in five 

 individuals, was made by drawing blood from animals which were 

 unexcited and in which the melanophore pigment was fully ex- 

 panded. The second series represents the sugar content of the 

 blood of five horned toads which were thrown into a state of 

 nervous excitement by stimulating the mouth with a weak induc- 

 tion current for thirty minutes and then waiting thirty minutes 

 before drawing the samples of blood. The third series represents 

 the sugar content of the blood of five horned toads into which 

 0.5 cc. of a 1 : 1000 solution of adrenin had been injected one hour 

 before. Table 1 shows the result of this experiment. 



