387 



Studies on Chromosomes. 



one pole of the nucleus. In stage b (contraction-phase, Fig. 

 they become closely massed in a spheroidal aggregation at the 

 center or toward one side of the nucleus, and surrounded by a 

 large clear space. At this time they stain so deeply that their 



FIG. 6. 



Lygaeus turcicus. a, contraction-phase of synaptic period (stage fe) showing large idiochromosome; 

 b, early post-synapsis (stage c\ both idiochromosomes shown; c, stage d, a plasmosome connected with 

 the large idiochromosome; d-f, chromosome-nucleoli (with plasmosome) from stage e; d and e single, 

 /, showing the two idiochromosomes; g, stage /, with plasmosome at its maximum size, and both idio- 

 chromosomes; h-n, chromosome-nucleoli from stage / (represented side by side near the plasmosome, 

 out of their natural position); h-k, four cases in which but one is present, l-n showing both idiochromo- 

 somes; o, stage g, with both idiochromosomes; p, q, stage h, two sections of the same nucleus showing all 

 of the eight chromosomes and a small plasmosome; r, stage ;, showing the six larger chromosomes and 

 the two idiochromosomes. 



