134 William A. Kepner. 



posed of a series of egg follicles remaining in connection with certain 

 nurse cells, that do not leave the terminal chamber, by means of 

 a protoplasmic strand, which the Germans have called Dotterstrange 

 or Dottergange and which Lubbock has named yolk ducts. The third 

 type involves, therefore, only the nurse cells as they lie within 

 the terminal chamber. Later it will be shown that Scolia dubia in 

 its nutrition combines the second and third types. 



Leuckart, '53, and Lubbock, 'GO, were the earliest writers to 

 describe the nutrition of the ovum by means of yolk ducts connecting 

 the ovum with the nurse cells of the terminal chamber. Claus,C., 

 '64, describes for Apis platanoides a very characteristic "Dotter- 

 strang" leading from groups of three to six nurse cells to the ovum. 

 Gross, '01, describes for Asopus bidens yolk ducts between the 

 follicle ova and nurse cells within the terminal chamber. Wielowieyski, 

 '06, in describing the ovary of the hemipter Pyrrhocoris apteris 

 says : ''Die Dotterzellen sind in einer Endkammer vereinigt und 

 werden mittelst feiner, im Karkraume derselben verlaufender plasma- 

 tischer Auslaufer mit ebensolchen plasmatischen Auslaufern der Ei- 

 zellen verbunden, so dass ein Ernahrungssystem entsteht, in welchem 

 dei einzelnen Dotterzellen mit den Eizellen direkt kommuniziren." 

 Kohler, '07, in the ovary of Xepa cinerea describes large yolk ducts 

 which lead from the terminal chamber and give off lateral branches 

 to individual ova. 



All the above forms show a nutrition involving nothing but yolk 

 ducts and occurring only through the yolk duct. In Scolia dubia 

 there are two phases of nutrition. The first phase is accomplished 

 within the terminal chamber through short yolk ducts of a peculiar 

 type. Not all the nurse cells take part in this first nutrition phase. 

 The second phase takes place from the nurse follicles and involves 

 all the nurse cells. 



The presence of extensive yolk ducts between nurse cells and ova 

 have in the past been taken as sufficient evidence that this was a 

 feature pertaining to the nutrition of the ova. The inference that 

 a nutrition phase of the ovum of Scolia dubia ensues within the 

 terminal chamber is based upon (a) the presence of short yolk ducts, 

 and (h) the condition of the nuclei of such nurse cells as are 

 attached by these ducts to the ova. 



