STAR CUCUMBER AND MAPLE APHIDS. II 



equal in size (fig. 94). Figures 95 and 96 are prophases of the first 

 maturation mitosis. 



The first and second spermatocytes of the woolly beech aphid have 

 such equatorial plates as are seen in figures 97, 98, and 99. The ana- 

 phase (figs. 100 and 101) is rather interesting, as here the lagging 

 chromosome is evidently the largest. 



The Star Cucumber Aphid. 



This aphid was discovered quite late, just before the frost killed the- 

 host plant, and only the sexual generation with the mothers of the 

 males and females was present. The males were winged and red, 

 the females pale green, and the mothers of the sexual generation were, 

 some red, others bright green. Here again the same mother gives 

 rise to both sexes. 



Some of this material was fixed in Hermann's fluid, and figures 

 102 to 105 were taken from the Hermann material. This fixation was 

 no better for the mitotic phases than that obtained with the Gilson 

 formula, but the nuclei of the young spermatocytes showed more defi- 

 nite structure (figs. 102 and 103). The plasmosome did not take the 

 haematoxylin stain, but remained a yellowish gray, while the chro- 

 matin appeared in a variously tangled and wound feathery spireme. 

 Figure 106 also shows the metaphase of the first spermatocyte and 

 figure 107 an early anaphase. Figure 104 is a prophase showing the 

 paired condition of one of the longer chromosomes, and figures 108 

 and 109 are pairs of daughter plates from the second spermatocyte. 

 In this aphid we have a marked difference in the size relation of the 

 chromosomes from that in the other species that have the same num- 

 ber. (Compare figs. 3, 23, 36, 105 or 106). 



The Maple Aphid. 



This is a pale aphid white with some brown markings. Its chief 

 peculiarity consists in the large number of chromosomes sixteen in 

 the spermatocytes. As shown in figure no, one chromosome is al- 

 ways much larger than the rest, and the other fifteen vary only slight- 

 ly in size. There are often two lagging chromosomes (fig. in) in the 

 anaphase of the first spermatocyte, and one daughter plate is usually 

 concentrated before the other, giving the unsymmetrical appearance 

 of figure 112. In figure 1 1 3 , a prophase of the first spermatocyte mi- 

 tosis, paired chromosomes are shown. The parthenogenetic forms 

 were not examined. 



