No. 529] 



NOTES AND LITERATURE 



03 



t/t<ra IfiiiKirckiaita, and suggests that the mutations which de 

 Vries observed are probably due to previous hybridization. 

 This is a very interesting suggestion, but the writer is 

 inclined to believe that the phenomena observed by de Vries 

 were due to a different cause. It is definitely proved that 

 in some of de Vries 's mutants the chromosome numbers are dif- 

 ferent from those of the parent form. Cytological investiga- 

 tions have also shown that in the reduction division in these 

 (Enothera mutants there are frequent irregularities in the dis- 

 tribution of chromosomes. It seems probable that de Vries 's 

 mutations are not the result of previous hybridizations but 

 rather are due to irregular behavior of chromosomes in the re- 

 duction division. If this is true then the phenomena observed 

 by de Vries would be due to a different cause from that which 

 presumably produced the results which Tower observed. In 

 the case of Tower's results we can explain the facts by the as- 

 sumption of simple Mendelian segregation. In de Vries 's work 

 there is evidence that the phenomena are due to a different 



It is gratifying that Tower takes a very broad view of the fac- 

 torial hypothesis of Mendelian phenomena. On page 323 he 

 remarks : 



This factorial point of view is in no wise, of necessity, to be tied to 

 or confounded with such speculations as the id-determinant-biophore 

 fabric of Weismann, nor with the pangene complex of de Vries, which 

 have no foundation in fact. 



This is the view which the writer has held for years and has fre- 

 quently set forth in these pages. I have also frequently pointed 

 out that we do not yet have sufficient knowledge of the phys- 

 iological processes of living matter to permit us at the present 

 time to formulate an adequate theory of the phenomena ob- 

 served in hybrids. I think we can, however, point out the gen- 

 eral nature of the causes underlying these phenomena, as I 

 have attempted to do in my theory of Mendelian phenomena. 10 

 In speaking of the difference in germ cells with respect to given 

 characters, he has the following to say: 



What this difference in the gametes is we do not know, but observed 

 behaviors are interpreted as being, most probably, due to the mechan- 

 ical separation into different germ-cells of whatever it is that produces 

 the contrasting attributes — segregation .lining gametogenesis. 



"American Breeders' Magazine, Vol. I, No. 2. 



