No. 524] CHROMOSOMES AND HEREDITY 4G3 



tation, that like chromosomes are at this time separated 

 and pass into daughter cells. If this is the correct in- 

 terpretation the process is one of profound significance 

 for students of heredity. 



It is true that in most cases a separation between the 

 united pairs can no longer be detected and this has been 

 interpreted to mean that an actual fusion takes place as 

 complete as when two drops of water unite into one. If 

 so there would be no grounds left for assuming when the 

 next division occurs, that the united halves actually sep- 

 arate again; for the splitting might occur along any axis 

 of the double chromosome as far as we know. I should 

 not care to make any dogmatic statements in regard to 

 this question in the present unsettled state of our knowl- 

 edge; but whether we assume the separation to be along 

 the line of union or whether in any other plane the con- 

 clusion will have, as I said, a deep interest for the stu- 

 dent of heredity. 



There is one additional piece of evidence that may be 

 cited in favor of the non-fusion interpretation. In some 

 insects one pair of chromosomes does not enter into 

 synapsis. These remain apart in the nucleus in some 

 species or simply touch each other without fusion in 

 others. In both cases the pair enters the spindle and 

 its members pass to opposite poles. 



Even more remarkable are such forms as Acholla, in 

 which one large chromosome lias a> its mate five smaller 

 ones. None of them fuse in synapsis, but they meet on 

 the spindle and four go to one pole and one— the larger 

 one — to the opposite. 



It may be argued that these cases show that the " pur- 

 pose" of the synapsis is only to bring together similar 

 chromosomes in order that they may be again sepa- 

 rated. It can not be denied that these cases give a certain 

 plausibility to this interpretation, yet they are excep- 

 tional cases, and it is unsafe to generalize from them to 

 other chromosomes that we know to behave differently. 

 Moreover, this method of " touch and go" appears to be 

 so much simpler than the elaborate changes involved in 



