620 Gro. W. TANNREUTHER, 
naked granular mass of protoplasm. The nucleoplasm is clear and 
finely granular. The chromatin is in a granular condition (Pl. 53, 
Fig. 117). All of the germ cells that enter the end chamber are 
potential ova, but all do not develop. This is more particularly 
true of the ova near the end of any generation. Only one ovum 
within the end chamber begins development at a time, although 
two to six ova may be present. Why one ovum within the end 
chamber at the proximal end begins growth in preference to another 
is a difficult question to answer. The growth does not begin until 
the ovum is connected with the nutritive string. This would seem 
to indicate very strongly that growth is initiated by the nutritive 
string. The cytoplasmic conditions of the ovarian glands, nutritive 
string and ova are very similar. LuBBock, 1859, maintained that 
the eggs and nourishing cells were modifications of the epithelium 
of the end chamber. METSCHNIKOFF, 1866, studied the formation of 
the end chamber in the viviparous aphids. The end chamber he 
says arises from a mass of cells in which the more peripheral become 
the follicular epithelium and the inner cell mass becomes the eggs 
and nourishing cells. This early interpretation was correct with the 
exception that the egg cells do not originate from the inner cell 
mass in common with the nourishing cells or ovarian glands, but 
originate from the follicular epithelium at the base of the end 
chamber. BazBrant, 1870, held that the ovarian glands and ova 
originate from a special nucleated mass of protoplasm in the center 
of the end chamber by a process of budding and that the ovarian 
glands were abortive ova or sister cells of the true ova. Further- 
more, he explained the attachment of the eggs to the central cell 
mass — ovarian glands — of the end chamber by their persistent 
union with the central cell from which they originated by division. 
Witt, 1885—1886, considered the ovarian glands of the end chamber 
as ooblasts, formed by a large nucleus surrounded by a very clear 
protoplasmic mass and that the nucleus of the ooblast divided into 
masses of the second order, which became scattered through the 
protoplasm. Each mass of chromatin is the origin of a vitellogene 
cell or an epithelial cell and that which remains of the ooblast 
nucleus becomes the germinal vesicle. These peculiar activities in 
the ovarian glands, — ooblasts —, as Wizz describes are present 
but their function concerns that of nutrition alone. KORSCHELT, 1886, 
in his paper on the origin and significance of the different elements, 
— nutritive, epithelial cells, etc., — says these elements are all 
