In fact, illustration so crowds on il- lustration, that I should weary your readers were I to write a tithe of those instances which occur to me, as affording evi- dence that antenna are given as tactors, and are only called into full activity when the opportunity of using eyes has in a great measure ceased.

Tactors are capable of a much more varied perception than we should on the first thought be in- clined to suppose.

A power may long remain dormant, if no circumstances occur to call it into action.

The human fin- gers become both fingers and eyes to the blind.

If then in the human species the fingers of one individual possess pow- ers, of which another can scarcely form a conception, how reasonable is it to suppose that the tactors of a cricket are still tactors in a grasshopper, although their employment as such may never be required.