70 



J. HERBEin lAVI.OK 



Fig. 1A. Ph.ajsi.' pholognipli of ualixed laiupbrush bivalent chromosome from an 

 oocyte of the newt, l^riturus viriilcscois (x650). Present evidence indicates that 

 DNA is the axial element which maintains the continuitj' of the material in each 

 of the loops extending from the main axis. (Original photograph contributed by 

 J. G. Gall.) 



