STUDIES ON GERM CELLS 497 
The general structure of the ovary and ovarioles was obtained 
from in toto preparations and from thick sections. Detailed 
studies were made of sections 4u thick and stained in the follow- 
ing ways: (1) Heidenhain’s iron hematoxylin; (2) Rubaschkin’s 
mitochondrial method;? (3) Altmann’s acid fuchsin; (4) Benda’s 
crystal violet; and (5) Delafield’s hematoxylin. These methods 
of fixation and of staining were selected in order that both 
cytoplasmic and nuclear bodies could be studied. 
The ovaries of insects consist of a number of tubes, the ovari- 
oles, which are attached at the anterior end by means of ter- 
minal threads and open at the posterior end into the oviduct. 
The variations in the structures of the ovarioles are due princi- 
pally to the presence or absence of nurse cells and the distribution 
of these when present. Certain ovaries, for example, those of 
the Orthoptera and Aptera, are not provided with nurse cells. 
In others the nurse cells may remain within a terminal chamber 
and supply the growing oocytes through a nutritive strand, 
as in certain Hemiptera and Coleoptera; or a rather definite 
number of nurse cells may become separated from the terminal 
chamber and accompany each oocyte, as in the Neuroptera, 
Hymenoptera, Diptera, and Lepidoptera. The result of the 
last named method of nutrition is the formation of ovarioles 
which resemble rows of beads. 
In the bee each oocyte is accompanied by a group of nurse 
cells. An outline of a single‘ovariole is shown in figure 1. The 
terminal filament (¢) consists of a row of long slender cells which 
extend entirely across the filament. Following this is a region 
occupying about half of the entire ovariole which is character- 
ized by rosettes of cells (r). These cells are apparently all alike 
* Rubaschkin fixes tissues in Meves’ modification of Flemming’s solution for 
one or two days. Sections are treated as follows: 
Potassium permanganate, } per cent..............2.eeeeees 1 minute 
Wash in water . 
Oxalic acid and potassium sulphate, } per cent............. 1 minute 
Peps) 10k TUT Ort See Oe arse eon a'e + oe vie = aes eels 15 minutes 
Beeric aluthy AGnermcemte y Soap eis ties sc « «oo «Lae ee 24 hours 
Wievsert a Memiapomplin .. oom. kee. slepss..s 6. as. 50a s age eee 2-3 days 
Differentiate in ferric alum, 2 per cent 
