558 
J. BRONTE GATE N BY. 
cells become arranged in two layers, and the outer layer in 
contact with the contents of the lumen becomes filled with 
grains stained with osmic acid, and the nuclei of this outer 
layer have their chromatin condensed into the form of 
crowded blocks. These cells are the nurse-cells. 
When the nurse-cells are formed certain elements in the 
inner layer beneath the nurse-cells augment in size. They 
undergo the progerminative indifferent stage, but then become 
altered in a different manner. The chromatin lumps of the 
indifferent cell break up and become oriented to the periphery. 
The centre of the nucleus then looks clear, while all around 
its periphery are collected little nuclein nucleoli (sic), united 
one to another by chromatin filaments. In this cell it is the 
cytoplasm which has grown most in size. Such is the history 
of the oocyte. This element does not undergo division before 
the maturation period. Ancel does not find in Helix the 
stages of primordial ovum or oogonium described in other 
oogeneses. 
According- to Ancel the presence of nurse-cells is a sine 
qua non for the formation of an oocyte, and is explanatory 
of its development. 
Concerning the growth period of the oocyte Ancel writes 
in the following sense : The chromatin of the young oocyte 
condenses into the form of little nucleoli, which become 
disposed around the periphery of the nucleus. A network 
becomes established at the expense of the nuclein nucleoli, 
and a new network is formed afterwards from the chromatin. 
In an involved statement Ancel describes the appearance of 
parachromatic nucleoli, distinguished from the nuclein nucleoli 
by double staining in haemalum and safranin. 
In the oocyte at an early stage one can find filaments in 
the cytoplasm. These filaments are originally dispersed 
through the cytoplasm, but later condense towards a peri- 
pheral zone, which diminishes more and more and disappears. 
During this time the whole cytoplasrrf takes on an alveolar 
appearance except at one place, where special bodies will 
soon put in an appearance. Hsematoxylin or safranin prepa- 
