It is quite possible, and I am inclined to consider it probable, that the pure dancer regularly inherits a tendency to whirl to the left, and that this is obscured in the case of the 200 line by the influences of a cross with another variety of mouse. It is to be noted that the individuals of the 200 line were predominantly mixed whirlers, and I may add that many of them whirled so seldom that they might more appropriately be classed as circlers.
THE INHERITANCE OF INDIVIDUALLY ACQUIRED FORMS OF BEHAVIOR
The white-black discrimination experiments which were made in connection with the study of vision and the modifiability of behavior were so planned that they should furnish evidence of any possible tendency towards the inheritance of modifications in behavior. The problem may be stated thus. If a dancing mouse be thoroughly trained to avoid black, by being subjected to a disagreeable experience every time it enters a black box, will it transmit to its offspring a tendency to avoid black?
Systematic training experiments were carried on with individuals of both the 200 and 400 lines of descent. For each of these lines a male and a female were trained at the age of four weeks to discriminate between the white and the black electric-boxes and to choose the former. After they had been thoroughly trained these individuals were mated, and in course of time a male and female, chosen at random from their first litter, were similarly trained. All the individuals were trained in the same way and under as nearly the same conditions as could be maintained, and accurate records were kept of the behavior of each animal and of the number of errors of choice which it made in series after series of tests. What do these records indicate concerning the influence of individually acquired forms of behavior upon the behavior of the race?
TABLE 53
THE INHERITANCE OF THE HABIT OF WHITE-BLACK DISCRIMINATION
Number of Errors in Daily Series of Ten Tests
MALES FEMALES
SERIES FIRST SECOND THIRD FOURTH FIRST SECOND THIRD FOURTH GENERA- GENERA- GENERA- GENERA- GENERA- GENERA- GENERA- GENERA- TION TION TION TION TION TION TION TION
No. 210 No. 220 No. 230 No. 240 No. 215 No. 225 No. 235 No. 245