CANNON: Stupres 1n Pranr Hyprips 165 
that is, the two sizes of rings found in the hybrid pigeon * and in 
some pure forms in plants + were not observed in the cotton. 
At the time when the chromatin segments are becoming con- 
densed and have gathered at one side of the nucleus, characteristic 
changes are also taking place in the structure of the perinuclear 
zone of cytoplasm. The inner portion of this becomes less dense 
and is finally replaced by a coarse reticulum of delicate proto- 
plasmic strands. This network unites with the nuclear wall on 
one side, and joins the more peripheral and unchanged portion of 
the perinuclear zone on the other. The reticulum is therefore 
from its genesis wholly of cytoplasmic origin. 
While the changes in the perinuclear zone are occurring as 
above described, certain developmental modifications may also be 
observed in the nucleus. Until this time the linin of the nucleus 
has not been noticeable, but now it assumes a more or less granu- 
lar appearance and stains feebly, and the nuclear wall shows indi- 
cation of approaching disintegration. Delicate threads of proto- 
plasm run out from it which join, on the outside, the circumnuclear 
reticulum, and on the inner side, the linin meshwork. Shortly the 
nuclear wall becomes entirely broken down and a continuous pro- 
toplasmic reticulum occupies the entire cell. 
The relation of the karyoplasmic reticulum to the perinuclear 
zone in the formation of the achromatic figure will be spoken of 
directly, and it may be premised that it is the same as is found in 
Cobaea scandens t and in Lavatera,§ as well as in other plants, that 
is the achromatic figure has elements drawn both from the cyto- 
plasm and from the nucleus. ae 
The topographic relations of the cell constituents at this time 
will be understood by referring to f. 7. When such a section ” 
treated with the Flemming triple stain, the perinuclear zone will 
be colored deep orange, the reticulum within the perinuclear zone 
will be colored lightly with the gentian-violet, and, finally, the 
chromatin will of course take the saffranine. 
*Guyer. Science, II. 11: 248. 1900. 
t Strasburger, Histologische Beitrage, 6: 42. 1900. oh ea er 
ary dle in 
t*’Lawson, Some Observations on the Development of the Karyokinetic Spindle 
; ‘ 808. 
P ollen-Mother-Cells of Cobaea scandens. Proc. Calif. Acad. Bot, III]. 1: 169. 189 
4 Byxbee, 2. «. 
