Plate II 



Harpswell willow aphid 



Fig. 30 Second spermatocyte, large, metaphase, three chromosomes. 



Fig. 31 Second spermatocytes, small, metaphase, two chromosomes. 



Fig. 32 Second spermatocyte, daughter plates. 



Fig. 33 Spermatogonium nucleus, prophase. 



Fig. 34 Similar prophase, drawn at two foci in same section, five chromosomes. 



Black milkweed aphid 



Fig. 35 First spermatocyte, metaphase. 



Fig. 36 First spermatocyte, metakinesis. 



Fig. 37 First spermatocyte, prophase. 



Fig. 38 First spermatocyte, anaphase. 



Figs. 39 and 40 First spermatocyte, telophase. 



Fig. 41 Second spermatocytes, small, of a similar nasturtium aphid, three chromosomes. 



Woolly beech aphid 



Fig. 42 First spermatocyte, anaphase. 

 Fig. 43 First spermatocyte, telophase. 



Saranac willow aphid 



Figs. 44 and 45 First spermatocyte, telophase, two stages. 



Ala pie aphid 



Fig. 46 First spermatocyte, anaphase. 



Figs. 47 to 49 First spermatocyte, telophase, three common types or stages. 



Fig. 50 First spermatocyte, metaphase. 



Fig. 51 Second spermatocyte, metaphase. 



Orange milkweed aphid 



Fig. 52 Equatorial plate of maturation spindle of parthenogenetic egg, exceptional case with seven 



chromosomes, 

 ^'g- S3 Usual case with eight chromosomes. 



Aphis cenothene 



Fig. 54 First spermatocyte, an early telophase. 



Fig. 55 First spermatocyte, later telophase, with the divided heterochroraosome (x) in one nucleus. 



Fig. 56 Second spermatocyte, large, prophase, five chromosomes. 



Fig. 57 Second spermatocyte, small, four chromosomes. 



