THE POLE DISC OF CHRYSOMELID EGGS. 



I«I 



mainly on staining reactions and the results of Blochmann (86)/ 

 Stuhlmann (86),^ and others who have described in various species 

 of hymenoptera a budding of the nucleus of the ovocyte resulting 

 in the formation of many small " nuclei " (Nebenkerne) each con- 

 taining small dark staining granules. The work of Sylvestri (08)^ 

 is also cited as supporting a nuclear origin of the pole disc. 



In connection with some work embodied in a paper now in 

 press, I have had occasion to study the process of nutrition in the 

 egg of Leptinotarsa signaticollis, 

 a chrysomelid beetle closely re.- 

 lated to L. deceinlineata, one of 

 the species studied by Hegner. 

 In this form the nutritive ma- 

 terial consists of a granular mass 

 secreted by the nurse cells of the 

 ovariole. This material enters 

 the egg through the egg-stringo.s 

 which is a protoplasmic process of 

 the egg terminating in the groove- 

 like spaces bet\yeen the nurse 

 cells. In safranin-lichtgriin prep- 

 arations these granules stain as 

 intensely with the basic dye as 

 the granules of the pole disc. 



Fig. I is a semi-diagrammatic 

 drawing representing a longitud- 

 inal section through an ovarycon- 

 taining developing eggs. The 

 eggs which in an earlier stage are 

 massed together in the proximal ningof the growth period. The nutritive 

 r .1 . -11, r stream {n.s.\ is represented in only one 



region 01 the termmal chamber ^ , , ^ . 



of the eggs (<?). e.s., egg string; n.c, 

 of the ovariole, gradually be- nurse cells ; ^.5. , ovariole stalk. 

 come arranged in a linear series 



in the ovariole stalk, the cells of which form the egg-follicles. 

 The egg-strings elongate as the eggs move down into the follicles, 



^ Festschr. Nat. Med. Vereins. Heidelberg. 

 2 Ber. d. Nat. Ges. Freiberg, I. 



^ Bolle. Lab. zojI. gen. e agr. delta R. Scuola Superiore d'' Agricoltura di Portici, 

 III., 1908. 



Fig. 1 . Longitudinal section of an 

 ovariole showing ovocytes at the begin- 



