No. 3.] THALASSEMA AND ZIRPHAEA. 605 



zag condition greatly obscures their true form, but in favorable 

 cases they appear double. In other preparations of unfertilized 

 eggs removed from the pouches, the chromosomes stand out 

 very plainly as black and often clearly double rods.^ In thus 

 demonstrating the presence of the chromosomes as double rods 

 throughout the entire growth period, my results agree with 

 those of Hacker ('92), Ruckert ('92), vom Rath ('92), and others. 



The chromosomes persist in the above-mentioned shape until 

 the asters commence to break through the wall of the germinal 

 vesicle, when they seem to undergo a concentration and approach 

 the asters. In entering the spindle, the chromosomes some- 

 times arrange themselves about the distal ends of the inner 

 rays, simulating the daughter-chromatin plates of an anaphase 

 (PI. XXXI, Fig. 10). By growth of the rays these two 

 groups become pushed together, meeting equatorially to form 

 the equatorial plate. Belles Lee ('97) has described a similar 

 phenomenon in Helix. 



The nuclear reticulum now shows a marked increase in its 

 affinity for haematoxylin, which increase continues until after 

 completion of the spindle ; the stain is retained with a tenacity 

 not surpassed by even the chromosomes or the centrosomes. 

 After complete extraction of the haematoxylin from the cyto- 

 plasm, and replacement by Congo red, the discarded reticulum 

 appears as a dense, thick-stranded, dark blue or black skein upon 

 a red background (PL XXXI, Fig. 11). After Flemming's 

 Triple, however, it is indistinguishable from the surrounding 

 cytoplasm, though after Auerbach's fluid, it takes the fuchsin 

 rather more deeply than the cytoplasm. The skein gradually 

 undergoes resorption, decreases in bulk and distinctness, and 

 finally fades out entirely, though traces of it are sometimes met 

 with as late as first polar metaphase with peripherally situated 

 spindle. 



While entering the spindle in the prophases, the chromo- 

 somes exhibit a great variety of forms, which in most cases are 



' It was these irregular black chromosomes that I described (Griffin, '96) as 

 "here and there . . . light thickenings or bunching together of strands of the 

 chromatic reticulum, which is doubtless a prelude to chromosome formation." 

 More extended study of later and earlier stages now shows them to be much- 

 tmsted ring or rod chromosomes. 



