[ 7 ] These dogs were born on 26 and 27 January, 1914. Compare the letter of Rolf in the "Communications of the Society for Animal Psychology," 1914, p. 28; and "The Soul of the Animal," p. 111.
[ 8 ] Ilse was barely two months old when she came into the possession of her master, on 20 April, 1914.
[ 9 ] The dog had become familiar with square roots in the course of earlier attempts.
[ 10 ] Frau Dr. Moekel taught another young dog, called Lux, as well as Roland, the former being taken over by a gentleman in Mannheim. In a protocol dated 14 June, 1914, I stated that Lux was able to do a certain amount of arithmetic at the age of four and a half months.