TnE SPEKMATOClENESrs (W DOMESTIC SIAilMAIÄ 217 



sph'omes of tliis stjige m-o still st:iin(xl dooply with mothyl-f^rcen (Fig. 131). 



At the oiul of this st.igo ii nucleolus jippcars, asually sitimtod close to 

 tho niK'lcjir \\:M (I''ig3. 131, 132). It is süiiimkI both with fnchsin n,u<l 

 methyl-gi-ccu at the same time with Atjerbach's iiM^tluxl, wliilo with ii'ou- 

 hnomatoxyliu it tikes the chromatin dye (Fig3. 19, 131). As tho nucleolus is 

 small in the Ix-ginning of this sfaige, it is difficult t3 distinguish it in tho 

 sections st;iined with iron-hasmatoxyliu (Fig. 18). Tho nucleolus grows rapidly, 

 increasing the staining capacity for acid-fuchsiu, while tho bulk of the cell 

 gi-adiuilly increases and the movement of the chromatin spiremes is carried 

 out further until they fill up the nucleas throughly (Figs. 19, 20). Tho longi- 

 tudinal splitting of chromosomes could not be observed iu this stage (Figs. 

 18-20). 



The early prophase : — With the growth of the nucleolus the chromatin 

 threads' become faintly staiued with ii'ou-hromataxyliu by wliich they show 

 gi'auuLar appearance, while with Aueebach's method they begin to stain 

 both Avith methyl-green and acid-fuchsiu at the same time (Figs. 21-23, 

 134). As will be shown in the subsequent chapter, it ssems more probable 

 that this change of staining capacity is duo to the chemiail change connected 

 .with the growth of tho chromosomes. With tho gi-owth of the cell this 

 chiiugc of the staining capacity proceeds more and more until it reaches 

 it? ituiximmn in the late proiDhase where the cells attain tho greatest zise 

 (Figs. 25, 27, 134). 



In this stage, beside the nucleolus, two chromatin masses appear, one of 

 which is liU-ger than the other (Figs. 22-24). They ai-e stainal in the same 

 manner as the ordinai'y chi'omosomes both with irou-hsematoxylin and with 

 Auerbach's method, a fact which induces one to think that these bodie3 may 

 be XY-chromosomes which exist in this stage as the chi'omosome nucleoli. 



The nucleolus grows rapidly till it finally attains its maximiun size at 

 the end of this st\ge (Figs. 23-25). At tho beginning of this stage tho 

 idiozome can clearly be seen, asually situated in close contact with the 

 the nuclear membrane (Figs. 132-134). 



I. This stage probably corresponfls to the diffuse or conEused period described by Wn-soN 

 ('12). In sime insects the diplotene-nuclei undergo remarkable transformation in which double 

 threads completely dlsnpiiear from view, giving rise to a diffuse, lightly staining net-like unclei. 



