THEORY OF EVOLITTIOX 



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Fic. (i:!. Conjugation of chromosomes (side to side union) in: 

 the s])eruiatnjienesis of Batraeoseps. (After Jaiissens.) 



some that meet in this way and always two of 

 tlie same kind. It has heen observed that as 

 the members of a pair come together they oc- 

 casionally twist arotmd each other (fig. 63, g, 

 1. and 64, and 6.5 ) . In consequence a part of one 



