This paper deals with the determination of the etiology of some forms of persistent headaches. The method under consideration will save time, is coupled with a great degree of accuracy, and requires no special knowledge of refraction and its correction by glasses. It will enable us to exclude other conditions as causes of certain persistent headaches, and consists simply in the use of a solution of sulphate of atropin instilled into the eyes. The method should be employed to determine the cause of persistent headaches.
It is probable that the results obtained are due to the effect of the drug on the innervation of the ciliary muscle, for after the accommodative power returns the headaches often reappear.
Concerning the explanations of headaches we may say that, in general, they are produced by some kind of irritation of the filaments of the fifth nerve, which supplies the dura mater. The following