RESEARCHES IN CROSS-EDUCATION, BY Walter W. Davis. ' I. Historical. The term “cross-education” has been used1 to express the fact that the effects of practice on one side of the body are transferred to the un¬ practiced side. The fact seems to have been first recorded by H. F. Weber. In a communication to Fechner,2 he reports an observation made on his son. The boy had been taught to write entirely in one sys¬ tem of penmanship, a system that employs a free-arm muscular movement. At the age of thirteen he was able to write reversely with the left hand —in so-called mirror-writing—without having practiced such writing in the least, although the letters were not so regularly made as those made with the right hand. The reverse writing, when viewed in a mirror, or when looked at through the paper as it was held to the light, appeared very similar to the boy’s ordinary hand-writing. Hence Weber con¬ cluded that by the training of the right hand in certain methods of pen¬ manship the left hand is also trained, unconsciously, to perform sym¬ metrical movements. He noticed also that others trained by different methods, or by several methods, failed in the test. Fechner reached a similar conclusion from an experience of his own. In the course of a series of observations in which he wrote the figure p many times, left-handed, he noticed that when he took the pen in his right hand, he would unconsciously write the figure reversed with a move¬ ment that was symmetrical to that made with the left hand. A certain method of writing had become so “impressed upon his mind” that it became natural to write reversely with the hand not used. 1 Scripture, Smith and Brown, On the education of muscular control and power, Stud. Yale Psych. Lab., 1894 II 115. 2 Fechner, Beobachtungen, welche zu beweisen scheinen, dass durch die Uebung der Glieder der einen Seite die der andern zugleich mitgeübt werden, Ber. d. kgl.-säch. Ges. d. Wiss., math.-phys. CI., 1758 X 70. 6