]^utritioii of the Ovnm of Scolia Dubia. 133 



having the migrated nuclei, no yolk nucleus is described. Similar 

 conditions are met with the ova of ants and wasps described by 

 Blochmann, '86, and in the ova of Musca described by Korschelt, 

 '86. That ova with these migrated nuclei fto aid them in the 

 handling of food material entering them from the nurse cells have 

 in no case a yolk nucleus is significant. It indirectly suggests that 

 the yolk nuclei of other ova are but accumulations of food material 

 that has entered the ovum more rapidly than the cytoplasm with 

 a single nucleus was able to transform it into yolk. 



These nuclei are the preparers of the food and are concerned 

 in but a secondary manner with the nutrition of the ovum in Scolia 

 dubia. 



We believe that we are warranted in recognizing two phases in 

 the nutrition of the ova of this wasp. The first phase runs its course 

 within the terminal chamber. The second involves the complete 

 history of "the nurse follicle after it leaves the terminal chamber. 

 The second phase, therefore, lies entirely outside the temiinal 

 cliaml>er. 



The follicle cells and theiV derivatives are now considered somatic 

 cells. Kohler, '07, writes : "Die Zusammengehorigkeit der einzel- 

 nen Zellen regelt sich f olgendermassen : Als gemeinsamen TJrspnings 

 sind anzusehen : die Zellen des Peritonealepitheles, des Endf adens, 

 des Eirohrenstieles, des Endkammer- und Follikelepithels. Diesen 

 somatischen Zellen stehen gegeniiber die Geschlechtszellen, d. h., 

 die l^ahrzellen und Keimzellen." 



I^urse cells and egg cells have long been known to be the chief 

 cells of insect ovaries. Stein, '47, first recognized them as two 

 distinct elements ; but considered them to be masses of homogeneous 

 protoplasm. Meyer, '-iO, recognized the cellular nature of nurse 

 cells and egg cells. 



Folsom, '06, uses a diagram from Lang's Lehrbuch to illustrate 

 his description of three types of ovaries of insects. The first type 

 is represented by ovary tubules composed of a chain of egg follicles 

 without nurse cells. The second type includes the tubules composed 

 of alternating egg and nurse follicles which arise out of a terminal 

 chamber. To the third type belong such ovary tubules as are com- 



