160 J. BRONT/2 GATENBY. 
PI. 11, fig. 12, and that the exceptional nucleus is an inter- 
mediate form. 
The nuclei at the anterior end of the egg are orientated in 
relation to the centre, as are those of the posterior. In the 
central region of the egg are found a number of black masses 
(Iron Hsematoxylin staining) of approximately the same size 
and shape as the excentric nucleolar mass of the blastoderm 
nuclei. That these masses are extrusions from the latter is 
proved by the fact that all stages in their expulsion can be 
found. In PI. 11, fig. 12, there were twenty- three in the 
egg. When the nucleolar mass is shot out towards the centre 
of the egg the nucleoplasm and the other granules break 
apart. The former disappears, the latter may be found in 
the egg (PI. 11, fig. 12, G. R. C.). In PI. 11, fig. 17, at X, 
there is a space left in the row of nuclei ; exactly on the 
same level, and quite near, are two nucleoli labelled Y. I 
believe that the empty space was occupied by the chromatic 
masses, both of which have lost their nucleoplasmic zone and 
their small granule. Additional proof that my conclusion 
concerning the character of these masses is correct will be 
mentioned below. In PI. 11, figs. 12, 13, 16, and 17, the 
central part of the egg is seen to contain extruded nucleoli. 
I have been able to count the number extruded in various 
eggs. 
In PI. 11, fig. 12, there were twenty- three ; in PI. 11, fig. 13, 
there were fifty-three; in PI. 11, fig. 16, there were twenty- 
four; in PI. 11, fig. 17, there were thirty; and so on, the 
number usually varying from twenty to fifty. In PI. 1 1, figs. 12, 
16, and 17, are younger than Pi. 11, fig. 13, so fewer nucleoli 
have been expelled. It is generally true that the younger 
the blastoderm, the fewer the extruded nucleoli. Examina- 
tion of the figures of blastoderm stages will fail to reveal 
any dividing nuclei, and none are ever found in the sections. 
It is quite obvious .that if it is true that nuclei are extruded 
and no division takes place, one should find a decrease in the 
number of nuclei in the growing blastoderm. Up to a certain 
point this is so. In PI. 11, figs. 12 and 14 are both longitudinal 
