266 



EMBRYOLOGY OF INSECTS AND MYRIAPODS 



and later some oi these yolk cells migrate into the mycetom. At the 

 posterior end the mycetom remains uncovered at first by the forming 

 blastoderm (Fig. 191), but later the blastoderm begins to thicken and 



V2 



'/. 



.y2 



gb 



_i_ 



am— tr*^ 



-i 



yc. 



Fig. 192. — Toxoptera. {am) Amnion. 



(gb) Germ band, (ser) Serosa, (y) Yolk. 



(y 2) Ovarian yolk (mycetom). (yc) Yolk 

 cell. 





Fig. 193. — Toxoptera. Sagittal sec- 

 tion, {am) Amnion, {gb) Germ band, 

 (po) Polar organ, (y) Yolk, {y 

 Ovarian yolk (mycetom). {ser) 

 {yc) Yolk cell. 



2) 



■^'^f*"^^^''-^ 





t— "■•■' 





po 



^ 



— yc 

 ser 



Fig. 194. — Toxoptera. Sagittal section of germ band, {am) Amnion, {ect) Ectoderm 

 {ent) Entoderm, {mes) Mesoderm, {ov) Developing ovary, {po) Polar organ, {ser) 

 Serosa, {y) Yolk, {yc) Yolk cell. 



invaginate, pushing the mycetom into the yolk. The mycetom is carried 

 inward until it lies well toward the middle of the egg, forming the base of 

 a cone the body of which consists of germ band and amnion (Fig. 192). 



