No. 2.] COMPARATIVE CYTOLOGJCAL STUDIES. 35 1 



" minute nucleolar granules " which were present in early stages. 

 In contradiction to the view of Scharff ('88) he finds that no 

 nucleoli wander out of the nucleus to form yolk globules. 



Delage ('95) opposes the view that the nucleoli and the 

 centrosomes are genetically related (as against the theory of 

 Julin ('93 b) and Wasielevsky). 



Galeotti ('95), embryonal cells of Triton and Spelerpes (fixa- 

 tion in Hermann's fluid with chloride of palladium substituted 

 for chloride of platinum ; stained for five minutes in sat. sol. 

 acid fuchsine in aniline water at 60° C, then stained in i^^ 

 sol. methylen green in equal parts of water and alcohol for three 

 or four minutes) : " Auf diese Weise erhalt man roth gefarbt 

 die Kornchen des Cytoplasma und alle Elemente des Kerns mit 

 Ausnahme des Nucleolus . . . ; gelblichgriin erscheint der 

 protoplasmatische Grund der Zelle und lebhaft griin die baso- 

 philen Granulationen." In the pancreas cells of Spelerpes the 

 green-stained nucleolus passes out of the nucleus and persists 

 as " Nebenkern," which in the cytoplasm seems to increase by 

 continued division ; and from this he concludes "dass der 

 Nucleolus ein endonucleares Arbeitsprodukt des Kernes ist, 

 bestimmt aus der Kernmembran auszutreten und im Cytoplasma 

 so umgeandert zu werden, dass er in Secretionsprodukte umge- 

 wandelt wird." 



Hacker ('95) first describes the nucleolar relations in the eggs 

 of Cantkocamptus, and then gives expression to general views, 

 based on his numerous previous observations, in regard to the 

 nature of nucleoli. Cantkocamptus stapliyliniis : in the smallest 

 eggs there is one large nucleolus, which increases in size, but not 

 to same relative extent as does the nucleus itself ; subsequently 

 vacuoles arise in it, one of which becomes a " Hauptvacuole " ; 

 smaller " Kernkorper " appear first when the chromatin elements 

 commence to thicken ; " wenn endlich die Kernsubstanz auf 

 das Minimum ihres Volumens zusammengedrangt ist, so fehlt 

 in der Regel jede Spur von nucleolarer Substanz." Then 

 follows his general conclusions in regard to the physiology and 

 structure of the nucleoli : " Die Nucleolen sind nach meiner 

 Ansicht im allgemeinen als nicht strukturirte Gebilde aufzu- 

 fassen. . . . Sie stellen als solche . . . ein Abspaltungsprodukt, 



