This paper presents a first report on an experiment closely similar to McDougall’s well-known experiment on the inheritance of the effects of training in rats, which has furnished what is probably the most important evidence of Lamarckian inheritance yet produced. McDougall’s reports on this experiment, which is still in progress, extend to the 34th generation of training, and his figures appear to afford strong evidence of an increasing facility in learning the particular task as the generations go on. McDougall’s three reports (the third in collaboration with Rhine) were published in 1927, 1930 and 1933, and will be referred to hereafter as I, II and III.
The experiment is so well known that it is only necessary to recall its nature very briefly. The rats are placed in a tank containing water, from which they can escape by either of two sloping gangways leading to a platform above the water...
