McDougall's experiment on the inheritance of the effects of training in rats has been repeated as closely as possible, except for certain improvements of technique. In both cases, the rats used are albinos, derived from the Wistar Institute.
Special attention has been paid to keeping the strength and duration of shock as constant as possible, since McDougall found that the former influenced the rate of learning.
The value of the number of errors made (shocks received) as a measure of learning capacity is discussed in detail.
Two independent lines have been maintained for five generations, and one of them for a sixth, each line being divided into parallel trained and control sublines, which have been tested against each other in each generation.
No increase in facility of learning by the trained sublines as compared with the controls has yet appeared.
The experiment is being continued.