416 * EGBERT W. HEGNER 



where it disintegrates into granules of a 'trophische Natur/ 

 Foot and Strobell ('11) have also compared it with the chro- 

 matin nucleolus in the oogonia of Protenor with which it has 

 certain characteristics in common, but no such differential 

 divisions occur as in Dytiscus. 



Govaerts ('13) has recently reported upon the differentiation 

 of the oocytes in Carabus, Cicindela, and Trichiosoma. He 

 was unable to find anything resembling the chromatic ring of 

 Giardina, and concludes 



. . . que la formation d'une masse chromatique, exteriorisant 



la differenciation entre I'ovocyte et les cellules nourricieres, est jusqu'a 

 present un fait isole, observe uniquement chez les Dystiscides. Mes 

 recherches demontrent que ce phenomene n'est pas applicable a tous 

 les Insectes, et qu'il faut chercher au fait de la differenciation, de ces 

 elements une cause plus large que la repartition inegale de certains 

 elements chromatiques. 



If no differential divisions are present, as in Dytiscus, what 

 is the cause of the formation of oocytes and nurse cells? Go- 

 vaerts decides that, since the ultimate oogonium possesses a 

 definite polarity marked by the locahzation of the 'residu fusorial,' 

 and the two kinds of daughter cells arise from opposite ends of 

 the mother cell, the cause of the differentiation resides in the 

 polarization of the oogonium. He does not, however, account 

 for this 'polarite pre-differentielle.' 



Ovaries of Leptinotarsa decemlineata were dissected out in 

 Ringer's solution and placed immediately in the fixing solution. 

 The fluids of Gilson, Altmann, Meves, and Carnoy were most 

 frequently employed. Sections were stained by Benda's method, 

 acid fuchsin, iron hemataxylin, and Mayer's acid hemalum. 

 The best results were obtained with material fixed in Meves' 

 modification of Flemming's solution and stained by the method 

 of Benda. 



The general arrangement of the cells in the ovary of an adult 

 beetle is shown in figure 9. The terminal chamber of the ovarian 

 tubule contains three kinds of cells, (1) nurse cells (n.c), (2) 

 young oocytes (2/.0.) and growing oocytes, and (3) epithe- 

 lial cells. The nurse cells and oocytes are both derived from the 



