THE THYKOID GLAND AND ITS DISEASES 



499 



iris, governed by the sympathetic, respond abnormally to the action of 

 epinephrin. 



It is true that this mydriasis test of Loewi is positive in the higher 

 degrees of hyperthyroidism, but the results are somewhat uncertain when 

 the test is applied to cases of latent or incipient hyperthyroidism. It 

 is, of course, in these cases that a test should be of the greatest use. 

 Loewi's test is of considerable interest, nevertheless, and confirmatory in 

 the higher degrees of hyperthyroidism which are, however, recognizable 

 without it. 



