60 THE PHYSICAL BASIS OF INHERITANCE 



with scrupulous equality, certainly to the first two cells of the 

 embryo, and probably to all later-formed cells. 



" The latter conclusion, which long remained a mere surmise, has 

 been rendered nearly a certainty by the remarkable observations 

 of Ruckert, Zoja, and Haecker. We must, therefore, accept the 

 high probability of the conclusion that the specific character of the 

 cell is in the last analysis determined by that of the nucleus that 

 is, by the chromatin ; and that in the equal distribution of paternal 

 and maternal chromatin to all the cells of the offspring, we find the 

 physiological explanation of the fact that every part of the latter 

 may show the characteristics of either or both parents " (Wilson, 

 1900, p. 352). 



4. Argument from Boveri's ingenious experiment. Taking a hint 

 from the experiments of the brothers Hertwig, who showed that 

 non-nucleated fragments of unfertilised sea-urchin ova (broken by 

 shaking) might be successfully fertilised and might segment, Boveri 

 (1889, 1895) showed that such fertilised fragments developed 



