624 Geo. W. TANNREUTHER, 
in Fig. 33. The ovarian glands have begun to disorganize A 
completely formed ovum is attached to the nutritive string. Some 
of the ova that have reached the end of the growth period do not 
undergo farther development. This condition is found only near the 
end of deposition when the aphid cease feeding. 
The condition of the ovogonia before the last ovogonial division 
is shown in Pl.49, Fig. 1—4. The cytoplasm is homogeneous. There 
is no definite cell wall. The chromatin granules collect and form a 
spireme (Fig. 2). The spireme divides transversely and forms six 
chromatin rods, four large and two small (Fig. 3—4). In the late 
prophase the chromosomes lose their identity and collect in a more 
common mass in the equatorial plate (Fig. 5), but in the late anaphase 
the chromosomes are more distinct (Fig. 8). The polar view of the 
telophase (Fig. 9) shows the reappearance of the two small and four 
large chromosomes. 
Immediately after the last ovogonial division, the ova enter 
the distal end of the end chamber and begin their period of growth 
as shown in Fig. 11. Before the ovum become connected with the 
nutritive string the nuclear area increases more rapidly than the 
cytoplasmic area, The ova at this stage of development are composed 
of a naked mass of cytoplasm, slightly granular, and a clearer 
nuclear area containing the six chromosomes. The chromosomes now 
break up into chromomeres. The chromomeres of the large and 
small chromosomes vary in size. Some of the chromosomes show 
four distinct chromomeres but this number is not always constant. 
The chromosomes (Fig. 12) become granular and lose their 
affinity for stain. When the ovum becomes connected with the 
nutritive string the cytoplasmic area increases more rapidly than 
the nuclear area or germinal vesicle. In Fig. 12 the condition of 
the ovum is represented as it enters the oviduct. The cytoplasmatic 
granules increases in size and become more variable. The cytoplasm 
next to the clear nuclear area becomes more dense and has the 
appearance of a nuclear wall or membrane. As growth continues 
(Fig. 13) the cytoplasmic area becomes vacuolated and has a slightly 
granular appearance. The chromosomes are collected into a single 
homogeneous mass. In the following stage of development (Fig. 14) 
the ovum becomes more elliptical. The vacuoles of the cytoplasm 
increase in size and show a more definite reticular condition. The 
nucleus is in the synapsis stage. 
The ovum at the end of the growth period (Fig. 15) shows a 
