Gottfried Engstler1 found that in 232 children in the first week of life, and with sound nervous systems, the plantar reflex consisted of dorsal flexion of the toes, whereas in two children there was plantar flexion and in eight no response was elicited on stroking the sole. Between the second and eighth week, ninety-nine showed dorsal flexion, one child showed plantar flexion, and eight gave no response. In the third half year, sixty presented dorsal flexion, thirty gave no response, and forty had plantar flexion. On the other hand, in the third year, five presented dorsal flexion, five gave no response, and ninety-five had plantar flexion.
M. A. Léri2 in 166 infants found extension of the toes on stroking the sole the rule at birth and flexion the exception, whereas after three years, flexion was the rule and extension the exception.
John Lovett Morse3 concluded after the
BURR CW. THE REFLEXES IN EARLY INFANCY. Am J Dis Child. 1921;21(6):529–533. doi:10.1001/archpedi.1921.01910360012002