PLATE XX 
Pirate XX, 1, 2. Photomicrographs of the pachytene chromosomes in 
the microsporocytes of triploid T'ripsacum larum Nash. The arrows in- 
dicate the internal knobs on the long arm of chromosome 5 (fig. 1) 
and on that of chromosome 8 (fig. 2). 750 > 
3. Photomicrograph of the pachytene chromosomes in the micro- 
sporocyte of T’ripsacum australe Cutler and Anderson. Arrow points to 
the internal knob on the long arm of chromosome 8. 750 >» 
