No. 528] 



NOTES AND LITERATURE 



759 



posed inheritance of acquired characters Darwin formulated the 

 theory of pangenesis, according to which each cell in the organ- 

 ism gives off a hud, or gemmule, which migrates to the germ 

 plasm and in the next generation becomes responsible for the 

 development of a corresponding cell in the now organism. De 

 Vries drops the idea of migration of the gemmules from the 

 organism into the germ plasm, and starts with these gemmules 

 as permanent constituents of the germ plasm. He also makes 

 other modifications in the nature of these bodies, and hence very 

 properly gives them a new name, "pangenes." 



I am of opinion that had de Vries taken an agricultural va- 

 riety of wheat for his studies he would have been led to the 

 development of a different theory. Unfortunately, he found 

 the mutations for which he was looking in a species which was 

 throwing off variants in a manner which we may well believe to 

 be unusual. In fact, de Vries examined over a hundred spe- 

 cies before he found one that suited him in this respect. Re- 

 cent cytological investigations by Gates, Miss Lutz and others 

 seem to justify at least the tentative assumption that the (Eno- 

 thera mutants arise from a change in the personnel of the chro- 

 mosomes. It is certain that in (Enothera gigas the Lamarckiana 

 the number of chromosomes has been doubled. Gates has shown 

 that in a general way the nuclei in gigas cells are twice the size 

 of those of Lamarckiana. Other mutants have numbers of chro- 

 mosomes not exactly corresponding with Lamarckiana. It is 

 also demonstrated that in Lamarckiana and several of its mu- 

 tants the course of events in the reduction division is abnormal. 

 A good many of the chromosomes do not unite into bivalents in 

 the usual manner, thus giving opportunity for all kinds of ir- 

 regularities in the distribution of the chromosomes. The fur- 

 ther fact that many of the mutants produce only a small pro- 

 portion of functional gametes at least suggests that in many 

 reduction divisions the chromosomes are distributed in such a 

 way as to interfere with the future development of the gametes 

 and the zygotes which would be formed from them. 



If we assume that the chromosomes, because of their relation 

 to the processes of nutrition or for other reasons, have an im- 

 portant influence on the course of development, and that there 

 are irregularities in the distribution of these bodies in the re- 

 duction division in Lamarckiana and its offshoots, we at once 

 find a satisfactory interpretation of the behavior of these mu- 



