128 
Transactions of the Society. 
EXPLANATION OP PLATE SHOWING THE BEHAVIOUR OF THE 
NUCLEOLUS IN THE LIFE-HISTORY OF LIMNJEA STAGNALIS. 
Lettering. — A, aster introduced into ovum by the sperm ; B, remains of 
basophil portion of the nucleolus ; BC, binucleate cell ; BP, basophil staining 
part of the nucleolus ; BV, nuclear vacuole staining faintly basophil ; C, nucleus 
of connective tissue cell of the trabecular wall of the ovatestis : CFj, CF 2 , cells 
which have recently undergone mitosis ; CH, chromosomes ; CL, cilia ; CP, cell 
at prophase stage of mitosis ; CR, masses of basophil staining substance in the 
nucleus, presumably chromatin ; CT, cell at telophase stage of mitosis ; DN, 
dividing nucleolus ; ED, endodermal cell ; ET, ectodermal cell ; FB, fragment of 
basophil staining substance derived from basophil part of nucleolus ; FO, fragment 
of oxyphil staining substance derived from oxyphil part of nucleolus ; FP, female 
pronucleus ; GA, element of Golgi apparatus ; GE, cell of germinal epithelium ; 
H, head of spermatozoon ; M, mitochondria ; ME, mesodermal cell ; N, nuclear 
membrane ; NC, sertoli or nurse cell ; NE, nucleolar extrusion into cytoplasm ; 
NL, nucleolus (oxyphil staining body or plasmosome) ; NP, pseudopodia-like 
process of the nucleolus ; NR, denser peripheral layer of nucleolus ; NV, vacuoles 
inside the nucleolus ; NX, substance probably of the nature of a nucleolar extru- 
sion ; NY, nucleolus disintegrating during formation of chromosomes ; OC, 
oocyte ; OP, oxyphil staining part of nucleolus ; OV, nuclear vacuole staining 
faintly oxyphil ; P ls first polar body ; P 2 , second polar body ; PN, nucleus of 
polar body ; PR, filament of protoplasm connecting developing head of spermato- 
zoon with nurse call ; R, nuclear reticulum ; SE, division spindle ; SG, granules 
formed as the result of secretory activities of the cell ; SN, male pronucleus ; SP, 
developing head of spermatozoon ; T, trabecular wall of ovatestis ; TL, tail of 
spermatozoon ; V, vacuole in cytoplasm ; Y, yolk granule. 
The oxyphil staining nucleolus (NL), and the substances extruded from it into 
the cytoplasm are shown in red, as are also certain granules which appear to be 
of the nature of nucleolar extrusions. These latter granules stain almost exactly 
similar to yolk granules, which renders accurate observations extremely difficult. 
The sperm heads at those stages of development when they stain oxyphil are 
also shown coloured red. 
All the figures are drawn from portions of the ova-testis fixed in corrosive acetic 
and stained with either Mann’s methyl blue eosin, or carmine and methyl green 
after the method of Obst. 
Explanation op Plate III. 
Fig. 1. — Cells of the germinal epithelium (GE), attached to the trabecular 
wall (T), of the ovatestis. 
Fig. 2 . — Young oocyte attached to the wall (T) of the ovatestis, showing the 
large oxyphil nucleolus (NL) and nucleolar substance (NE) passing out into the 
cytoplasm. 
Fig. 3. — Oocyte with nucleolus differentiated into oxyphil (OP), and basophil 
(BP) staining portions. Nucleolar extrusion occurring at NE. Cytoplasm filled 
with yolk granules. 
Fig. 4. — Nucleus of an oocyte showing the extrusion of oxyphil substance 
(NE) and the disintegration of the basophil nucleolus (BP). 
Fig. 5. — Nucleus of an oocyte at a later stage of development, showing the 
remains of the basophil nucleolus (B), and the basophil substance (FB), scattered 
upon the nuclear network. Extrusion of oxyphil substance (NE) is still proceeding. 
Fig. 6. — Oocyte at about the same stage of development as in fig. 5. The 
basophil nuclear substance (FB) is scattered throughout the nucleus and extru- 
sion of the oxyphil substance (FO) is continuing (NE). 
Fig. 7. — Nuclei of three spermatocytes (a, b, c) showing the appearance of the 
nucleolus (NL) during synizesis. 
Fig. 8. — Oocyte (OC) attached to trabecular wall (T), surrounded by “nurse ” 
cell (NC), to which are fixed developing spermatozoa (H). 
Fig. 9. — “Nurse” cell (NC) being drawn out, away from trabecular wall (T) 
by metamorphosing spermatids (SP). The elongated nucleus of the “nurse ” cell 
has two large nucleoli. 
