11 



HEREDITY 



INTRODUCTION 



Amongst many otiicr problems of heredity, Professor 



Pearson and liis pupils have investigated the inheritance 



of stature in man. They proceeded by measuring, in a 



great many instances, the height of a father and one or 



more of liis sons. The average height of all the men 



measured was about five feet eight inches. It was 



found that if one considered by itself the group of 



fathers measuring about six feet, the average licight of 



their soas was about five feet ten. Further, if one took 



by itself the group of fathers measuring five fecst six, 



the average height of their sons was about five feet 



seven. That is, tall or short fathers tended U) hav(; tall 



or short sons respectively, but the resemblance as regards 



stature was only partial. In other words, variations in 



stature were inherited, but only to a limited extent. 



Professor Johannson of Copenhagen has carried out 



an investigation on similar lines with regard to the 



size of the seed in beans. Taking the seeds from a 



single plant, he separated the large from the small, and 



planted each lot separattjly. From the resulting plants, 



when ripe, ho took the seeds and w(;iglied them ; ho 



found no difference in the average size of the seed in 



the two lots. He repeated this experiment several 



times, and kept on selecting for several generations, 



but always with the same result. Variations in the 



size of seed, witliin a single race, were not inherited 



at all. 



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