14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



of the genital ridges each gonad in the female comes to be suspended 

 from the splanchnopleure by a cellular sheet (fig. 3 E, a). This 

 suspensorial sheet Heymons calls the Endfadenplatte, since it is des- 

 tined to form the terminal filaments (Endfaden) of the ovarioles. 

 A thickening of the fold along the lower border of the ridge forms 

 a ventral strand of the gonad (6), which gives rise to the ovariole 

 pedicles and the calyx of the oviduct ; posteriorly it is continuous with 

 the free part of the lateral duct. The middle part of the gonad {Grtn) 

 between the suspensional dorsal plate and the ventral strand contains 

 the germ cells, and is therefore the germarium, or region of the primi- 

 tive ovary from which are formed the egg tubes of the definitive organ. 



The germ cells at this state, as described by Heymons in Blattella, 

 are evenly distributed throughout the length of the median part of 

 the gonad, and the organ increases in thickness owing to a multiplica- 

 tion of the germ cells. The dorsal plate now separates from the wall 

 of the body cavity, and its flat, elongate cells become arranged in about 

 20 vertical rows (fig. 3 F, TF). These columns of cells form the 

 terminal filaments of the definitive ovarioles. The first appearance of 

 the tgg tubes is indicated by a series of dorsal swellings of the middle 

 region corresponding with the columns of filament cells. Then the 

 swellings are converted into definite ovarial lobes by a deepening of 

 the grooves between them (C), until finally the gonad is cut vertically 

 into separate compartments as far as the ventral stranf^. The com- 

 partments are the ovarial tubes, each of which is covered by an epi- 

 thelial layer of mesodermal cells, and contains a number of tgg cells 

 (GCls). In the larva of Clocon dimidiatum, Lubbock (1863, 1866) 

 observed that the ovaries are at first long cylindrical organs, each con- 

 sisting of a central body with short lateral lobules. By the end of 

 larval life the lobules have enlarged and have taken on the form of 

 typical ovarial tubules. The developmental processes in these com- 

 paratively generalized insects would seem more probably to represent 

 a primitive condition than that described by Seidel in the specialized 

 hemipteron Pyrrhocoris apierus, in which the definitive genital tubes 

 are said to be developed directly from independent segmental gonadial 

 rudiments. 



The exit apparatus of the egg tubes is formed from the ventral 

 strand of the gonad, which becomes cleft between the attachments 

 of the tubes upon it, and thus divided into the rudiments of the 

 ovariole pedicles (fig. 3 G, Pdcl). The undivided part of the ventral 

 strand and its posterior continuation become the lateral oviduct (Odl), 

 the anterior end of which supporting the pedicles is widened to form 

 the calyx (CLv). By a shortening of the calyx, the egg tubes of the 



