The alopecia to be considered in this paper is the form of the disease that so commonly affects young adults, and which has no observable connection with any other disease.
In the male, this form is of very frequent occurrence. In the female, on the contrary, it is comparatively infrequent. Now, when a farmer finds his expected crop of wheat or corn a failure in some places, and a success in others, he at once asks himself: how does the soil where the failures exist differ from that where the crop is satisfactory? Is it, in comparison, more wet or more dry, more stony or more sandy, or what is the difference, for difference there must be, otherwise the crops would be the same? In the same manner, the investigator, seeking the cause of alopecia, and finding the disease common in one sex and rare in the other, may ask