No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 365 



mehrerer blauer Kiigelchen hervor. . . . Nach ihrem chemischen 

 Verhalten stehen also Nebennucleolus und Nucleolus einander 

 naher als Haupt- und Nebennucleolen "; he concludes that the 

 " Nucleolus " and the " Nebennucleolus . . . mindestens ver- 

 schiedene Modificationsstufen des Paranucleins . . . darstellen." 

 Mytihis egg : what Lonnberg supposed to be vacuoles within 

 the nucleoli, List holds are " Nebennucleoli," and these alone 

 evince the characteristic Berlin-blue reaction ; by afterwards 

 staining the preparation with carmine, "die Masse des Haupt- 

 nucleolus, das Nuclein, hatte sich scharf roth gefarbt, die 

 Nebennucleolarsubstanz, das Paranuclein, rein blau." Even in 

 eggs where no yolk was as yet present, both these substances 

 could be demonstrated. The " Hauptnucleolus " represents 

 the greater part of the nucleolus, and is usually single ; in it 

 may lie one spherical " Nebennucleolus," or the latter may 

 cover, cap-like, one pole of the former; sometimes "Nebennucle- 

 oli " occur in the nuclear cavity, separated from the " Haupt- 

 nucleolus"; occasionally there are true vacuoles within the 

 latter. Plwlas egg : (treatment with iron chloride, nitric 

 acid, then " Ferrocyankaliumldsung ") the " Nebennucleolus " 

 is much larger than the " Hauptnucleolus," except in very 

 small ova, where they may be equal in size. The last-named 

 nucleolus may enclose a large, excentric vacuole, or in place 

 of this, a "Nebennucleolus"; in the chromatin network of 

 the nucleus there are small nodules of paranuclein, and some- 

 times a free "Nebennucleolus." "In alteren Eiern iiberwiegt 

 bei Weitem der Nebennucleolus den Hauptnucleolus an Masse " ; 

 the latter is either apposed to one end of the former, or there 

 may be a large " Nebennucleolus" with a small " Hauptnucle- 

 olus " at each end of it. Pristinriis egg : in the youngest 

 germinal vesicles the minute nucleoli all lie at the nuclear 

 periphery, the larger ones being central ; in larger ova all the 

 nucleoli are placed at the periphery of the nucleus. Sphaere- 

 chinus egg : the supposed (Hacker, '93b) vacuole of the " Neben- 

 nucleolus" is in reality the "Hauptnucleolus" : "Jedoch weichen 

 meine Resultate von denen Hacker's darin principiell ab, dass 

 eben festgestellt werden konnte, dass das, was H. Hauptnucle- 

 olus nennt, wie ein Nebennucleolus reagirt, und die Vacuole 



