Katharine Foot and E. C. Strobell 31 
Oo 
PHoto. 9. In this spermatocyte the heavy chromatin reticulum shows a 
longitudinal split in several places. The persisting plasmosome is somewhat 
distorted by the technique. 
Puoto. 10. A little later stage, where the chromatin is in the form of 
loops, many of them showing a longitudinal split. The plasmosome at the 
upper right hand periphery has been somewhat distorted by the technique. 
PuHortos. 11 ann 12. At this stage the chromosomes are beginning to assume 
a definite form, and the round densely staining plasmosome is still present. 
PuHorTos. 138, 14, anp 15. Later stages where the form of the chromosomes 
is becoming clearer, and some of the characteristic Shapes can be recognized. 
In Photo 13 an abnormal condensation of the chromatin can be seen in 
several chromosomes. The persisting plasmosome is present, on the upper 
periphery of the three preparations. 
PuHoro. 16. A little later stage where the form of the chromosomes is 
more compact. Close to the chromosome on the upper periphery a faintly 
stained plasmosome is seen. This is the latest stage at which we have 
demonstrated the plasmosome. 
PuHoto. 17. X about 2000. Reproduction of Wilson’s drawing b from his 
Figure 2 in “Studies on Chromosomes,” II. Section of ‘spermatocyte nu- 
cleus of Anasa tristis late growth period,’ showing 5 chromosomes and struc- 
ture marked h, the odd, heterotropic chromosome. Persisting plasmosome 
indicated under p. 
PuHotTos. 18, 19, ANp 20. Early prophases about the same stage shown in 
Wilson’s figure (Photo. 17). In these preparations all 11 chromosomes are 
present. For identification of eccentric chromosome in these photographs, 
see page 287. 
PuHotos. 21 to 24. Early prophases. All the 11 chromosomes are present 
and each preparation shows 9 tetrads, the 2 microchromosomes, and the 
eccentric chromosome, which can be readily recognized by its form,—two 
parallel rods straight or sometimes slightly curved. For detailed description 
of this chromosome, see page 287. 
PLATE II. 
Puortos. 1, 2, AND 8. Early prophase showing characteristic shapes of the 
chromosomes. The eccentric chromosome can be recognized by its typical 
form of two parallel rods. In Photo. 3 the microchromosomes are unusual 
in size and form. 
Puoto. 4. Early prophase. In this preparation all the ten large chromo- 
somes, including the “ eccentric”’ are tetrads. 
Puotos. 5 To 10. Later prophases, when the chromosomes condense and 
are somewhat smaller than at the early prophase. In all these preparations 
the eccentric chromosome can be identified by its characteristic form. 
PuHoros. 11 tro 19. Late prophase or metaphase showing the typical ring 
arrangement of the chromosomes with the eccentric as a rule, outside the 
circle. The eccentric retains its typical form in all these preparations, al- 
though at this stage the rods become shorter and thicker. 
