The Behaviour of the Nucleolus during Oogenesis. 125 



apparently ampliophil, from which are budded off into the 

 karyolymph two kinds of bodies— namely, amphophile bodies 

 which develop a basophil cap, and oxyphil granules. During 

 growth these become scattered throughout the nucleus and 

 eventually arrange themselves peripherally as " Eandnukleolen," 

 The behaviour of the nucleolus in this species is very different 

 from what is described below in another member of the same 

 genus, a difference which emphasizes the striking cytological 

 dis-similarities which occur in closely related oi-ganisms. 



Technique. 



The material used in the present investigation was fixed either 

 in corrosive acetic or Bouin's modified solution, picro-formol 

 acetic acid. The best staining results were obtained by using 

 Mann's methyl blue eosin, which stained the nucleoli red, blue or 

 purple according to the stages of development of the oocyte. The 

 same histo-chemical reactions, however, resulted from the use of 

 Unna's methylene blue and eosin, lichtgriln and safranin, or 

 hsematoxylin and eosin used according to Scott's method. Nucleoli 

 at similar developmental stages which stained blue with methyl 

 blue took up the green stain when lichtgriin and safranin were 

 used, or coloured purple when hematoxylin and eosin were em- 

 ployed. Such nucleoli are therefore referred to in this paper as 

 . the basophil nucleoli, while those nucleoli which colour with eosin 

 or safranin are referred to as the oxyphil nucleoli. 



In preparations made by the Mann-Kopsch method ( 11), stained 

 with acid fuchsin and differentiated in picric acid, similar pictures 

 were obtained as with the fixatives previously mentioned. However, 

 the difference in staining reaction of different parts of the nucleolar 

 content of the nucleus, although noticeable, was not so striking as 

 with the other techniques. Sections fixed by the method of 

 Mann-Kopsch were treated with potassium permanganate solution 

 to rectify the loss of staining properties due to the osmic acid, and 

 then treated with Mann's methyl blue eosin, but although the 

 same essential results were obtained the Staining reaction was not 

 satisfactory. 



The acetic acid fixatives have the further advantage over 

 chrome-osmic acid when dealing with the nucleolus and nucleolar 

 extrusions, as the chrome-osmic preserves the mitochondria, and 

 these stain with acid fuchsin similarly to the nucleolus and its 

 extrusions, and so render it difficult to distinguish between the two. 



Cheomophility of the Cytoplasm of Patella. 



In preparations made by fixation in corrosive acetic or Bouin 

 with acetic, and stained by so-called acidic and basic stains, the 



