I am afraid that what I am going to place before you to-night will be somewhat incomplete. This is unavoidably so because I have not had sufficient time at my disposal to test my views thoroughly. The evidence which I have to offer, therefore, in support of my case is necessarily scanty, and it would be premature to force unwarranted conclusions from it. Moreover, what little testing I have done has been confined almost wholly to one special problem. On that account there is a danger that my presentation of the topics will appear to lack proportion. I hope, therefore, that you will bear these facts in mind when judging this paper, for otherwise your verdicts could not be altogether fair.