442 Transactions of the Society. 



Man. Competent observers have stated that the cells of the male 

 negro have twenty-two chromosomes, and it is probable that the 

 negress has twentv-four, at least in some cases. Now, in the 

 white man and woman the ennmerations of Winiwarter and others 

 have usually been forty-seven and forty-eight, though sometimes 

 thirty-two or thereabouts. It seems curiously difficult to reach 

 certainty in regard to this simple point, but there is no harm in 

 asking, as Gates does, whether the white man may not have 

 originated from a black race by a " tetraploid mutation and its 

 consequences." 



The nuclear changes studied in (Enothera in their association 

 with particular mutations are not restricted to changes in the 

 mimher of chromosomes ; they may concern their shape, size, and 

 structure. What has been gained is a demonstration that in some 

 cases bodily peculiarities of mutants are correlated with visible 

 changes in germinal organization. 



Now, one is not unaware that this is just telescoping-down 

 the Proteus of the full-grown organism into the gerui-cell phase of 

 its being, and that a recognition of germinal disturbances does not 

 tell us what conditions them. As Bateson has often said, we find 

 ourselves confronted with the oppressive difficulty of cell-division 

 and irregularities in its procedure. Yet there is an enlightening 

 gleam in the proof that somatic mutations are correlated with 

 antecedent germinal disturbances, for we know that abnormal cell- 

 divisions occur in various conditions in nature, and we have 

 already referred to the opportunities for re-arrangenients that occur 

 in the early history and maturation of the germ-cells. Is there any 

 further light ? 



(c) We must remember that chromosomes are living units in a 

 complex environment, and just as Bacteria sometimes change 

 suddenly in their physiological properties, so chrosomomes may 

 vary in then- stereochemic architecture or in functional powers. 

 Moreover, it is not fanciful to suppose that these vital units, which 

 have great persistence of " individuality," may exhibit age-changes 

 or periodic re-organization processes. 



Here may be profitably considered the recent work on the 

 Slipper - Animalcule {Paramecium aurelid) by Woodruff and 

 Erdmann. Woodruff has kept a pure line of this Ciliate healthy 

 for over seven years, through more than 4500 generations. As is 

 usual in a pure line all descended from one there was no conjuga- 

 tion. On an average of once a month, however, a remarkable 

 regulatory process occurs, which the authors call endomixis, which 

 secures the indefinite life of the race. Nuclear changes, com- 

 parable to those that precede conjugation in normal wild conditions, 

 set in : the old nuclear material, both macronuclear and micro- 

 nuclear, is disintegrated and re-organized ; but there is no forma- 

 tion of stationary and migratory micronuclei as there is before 



