127 
The Morphology and Physiology of the Nucleolus. 
which they adhered, and they were then plunged into either Bouin 
or corrosive acetic. Steel needles were unsatisfactory for this pur- 
pose, as the eggs tended to stick to their surface and then immersion 
in the fixing solution caused corrosion. 
Ultimately, very finely drawn out threads of glass were 
utilized with most excellent results. 
The method I therefore adopted for the preparation of the eggs 
and embryos was as follows : — The egg clusters were removed from 
the aquaria and laid on filter paper. Each cluster was cut in 
halves with a fine pair of scissors. With a small knife blade the 
eggs were then scraped out on to filter paper and rolled about 
so as to get rid of the adhering mucilage from the outer envelope. 
The filter paper was then moistened and placed in position under 
a simple microscope. Each egg was then manipulated with two 
glass rods made by drawing out rods of glass of small diameter in 
a flame. With a curved rod each egg was rolled over and over 
until it no longer adhered to the moist filter paper but moved 
quite freely. It was then stabbed with a finely pointed glass 
piercer, to which it adhered. The piercer was then dipped into 
the fixative, when the eggs immediately slid off. The fixative 
was contained in a small glass tube about f in. in diameter and 
1 in. in height. After fixation the various alcohols were trans- 
ferred to the material while still in the same tube, the liquids 
being drawn off by pipettes. Finally, the embedding in wax was 
completed in the same vessel, and when the wax hardened, the 
tube was carefully broken open and the solid wax block removed 
and serial sections cut in the usual manner. 
The fixation which gave the best results was corrosive acetic, 
1*5 p.c. acetic acid and 98*5 p.c. saturated solution of corrosive 
sublimate, for about three or four hours. 
This method has the great advantage of enabling large numbers 
of eggs and embryos to be dealt with at the same time, and the 
process can be performed quite expeditiously. 
The Bkhaviour of the Golgi Apparatus and Mitochondria 
DURING GaMETOGENESIS AND EmBRYOGENY. 
Observations on the extrusion of solid substances from the 
nucleus into the cytoplasm recorded previously to the discovery 
of cytoplasmic organs have been open to criticism, on the grounds 
that there has been confusion between these organs and chromidia 
or nucleolar extrusions. 
Mitochondria and Golgi apparatus, as is well known, are 
preserved by fixatives which contain certain chrome salts and 
osmic acid, but destroyed by acetic acid. In some cases, however, 
when both osmic acid and acetic acid in small proportions are 
present, the mitochondria may remain badly preserved in the 
