Experiments were made on 10 guinea-pigs, 10 rabbits, 10 rats, 9 pigeons, 6 dogs, 3 cats and 3 monkeys. Strughold finds it very probable that the high sensibility of the center of the cornea (4 to 5 times higher than near the margin) depends upon the richness in nerve endings in this part of corneal epithelium compared with the marginal zones, as is described by a number of histologists. For experimental purposes it follows from this result that it is necessary, for comparison from case to case, to examine always the same point. The most practicable point is the center of the cornea, the threshold-values of which, concerning the usual laboratory animals, have been found to vary little.