274 BOTANICAL GAZETTE | APRIL 
stain black with iron-aium-haematoxylin have taken a character- 
istic position. Some, however, which do not retain the stain, 
are scattered through the nucleus. /ig. 77 shows a somewhat 
later stage. Only traces of the network are now visible; the 
granular condition is becoming quite pronounced and the nucleoli 
are arranging themselves in the form of a ring. The structure 
within this ring I was not able to make out definitely, but in 
most cases it seemed to be finely granular, with traces of threads 
more or less defined. 
In fig. 18 every vestige of the network has disappeared, and 
the nucleus is filled with an evenly granular substance. Nearly 
all the nucleoli have collected at the center. In fig. 79 the 
groundwork of the nucleus shows a beautiful reticular structure, 
exactly like that of the cytoplasm outside the nucleus. The 
nucleoli are taking the form of elongated masses which repre- 
sent definitely the chromatin of the nucleus. The threads seen 
in the central area area part of the general reticulum. oe 
The development of the male pronucleus was not studied i 
detail, but several stages, one of which is shown in ig. 73, indicate 
that the sequence is similar to that just described for the nucleus 
of the oosphere. ‘ned 
It seems probable that various bodies have been descn 
under the term nucleolus. That some of these nucleoli 7 
sent chromatin has been proved both in animals and in per 
In animals the sequence described by Carnoy and eapay 
batrachians agrees more nearly with the conditions 1 i 
That the chromatin in the resting nucleus of Spirogyré : ae 
form of a nucleolus has been shown by several meee" 
notably by Mitzkewitsch3. A chromatin nucleolus a 
described by Davis ¢ for Corallina, one of the red alge = the 
tion between chromatin and nucleoli has been noted 18 
*La vésicle germinative et les globules polaires chez les batrachiens- 
14: 113-200. 1898. ’ 
3 Ueber die Kerntheilung bei Spirogyra. Flora 85: 81-124. 1898. ie a 
*Kerntheilung in der Tetrasporenmutterzelle bei Corallina officinalis L- ; 
ferranea. Ber. d. deutsch. bot. Gesell 16 : 266-272. 1898. 
