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THE AMERICAN NATURALIST [Vol. XL VII 



F x there is no break in the continuity of its manifesta- 

 tions between sporophyte and gametophyte, even though 

 reduction and probably segregation have occurred. And 

 should we not expect to see such a break if segregation 

 by chromosomes took place in sporogenesis? 



The evidence as a whole I think, warrants one in the 

 suggestion that chromosomes are characters of the zygote 

 and gametophyte, on the same footing in development 

 with other plant characters. It is more difficult to com- 

 prehend this conception of these bodies, because they ap- 

 pear as characters in the development of the cell, rather 

 than in the development of the larger unit, the individ- 

 ual organism. They are characters in the sense that they 

 disappear and reappear at a place and time in the life 

 history of the organism which we can predict. They can 

 be transferred from one race of organisms to another 

 provided fertile F t hybrids are possible. They are in- 

 fluenced in as definite a manner, by the underlying cause 

 represented by the term factor for abnormalness, as are 

 the zygotic expressions included in the word fasciation. 



Concluding, I realize these speculations are largely 

 negative in character, but they are in accord with a stead- 

 ily growing skepticism among students of genetics as to 

 the importance of chromosomes in inheritance, and their 

 relation to segregating Mendelian characters. The im- 

 pression has been distinctly gained from a study of this 

 abnormal strain and its crosses with the normal that 

 chromosomes are not the omnipotent creators of destiny, 

 but characters on the same footing with other structures. 

 The same dynamic forces, whatever they are, are chang- 

 ing and modifying these chromosome characters in the 

 same capricious manner as those of a grosser nature. 

 One would be inclined to ascribe these changes to an 

 ultra-microscopic parasitic organism were it not for the 

 experimental evidence in F„, which precludes such a be- 

 lief. 



My warmest thanks are due Dr. E. M. East for sugges- 

 tions and criticisms while engaged in this investigation. 



July, 1912. 



