214 



C'akültne MeGiLt.. 



is a second layer of flattened cells, the lollide-cells [h in Fig-. 1. 89 

 and 40), wliicli are directly derived from oogonia. 



Each egg--string shows the following regions: end-filaraent, ger- 

 minal area and growth-area. Of conrse in the imagu there is in 

 addition to these an area of maturation, but this final stage in the 

 development of the ova has not yet been worked out. The three 

 regions will be described in order. 



1. The End -filaments. 

 The end-filament {c in Fig. 1 and 89) consists of a single row 

 of cells stretched out into a long thread. Its anterior end passes 

 forwards to the dorsal body-wall, giving attachment to the egg- 

 strings, and posteriorly its cells constitute the primitive ova. some 

 of which undergo little differentiation and persist as follicle-cells 

 wedged in among the remaining cells which develop into oogonia. 



The cells in the end-filaments have indistinct boundaries, lightly 

 staining cytoplasm, oval or round nuclei containing little chromatin. 

 A small nucleolus is present even in the youngest cells. This is a 

 true nucleolus, being composed of para-nuclein and staining with 

 ordinary oxyphile dyes, llironghout the length of the filament, ex- 

 cept in a few cells just in front of the germinal area, the nuclei 

 lie with their long axes parallel to the long axis of the thread. 

 €lose to the germinal area, the cells have their nuclei arranged 

 with the long axes perpendicular to that of the end-filament, an 

 arrangement which affords a firmer attachment for the egg-strings 

 {d in Fig. 1 and 39). Mitosis, though not frequent, does occur in 

 the region of the end-filament adjoining the germinal area (Fig. 1). 

 The anterior ends of the filaments unite to form a ligament 

 which runs just ventral to the pericardium. Johamnes Müller i 1825). 

 noting the close relation of the end-filaments to the pericardium, 

 concluded that they were blood-vessels conveying nutriment to the 

 ovary. Leydig (18B5) regarded the elements of the t-nd-filaments 

 as the homologues of the germ-cells. Korschelt (18S6i in Ortho- 

 ptera found the filament-cells passing directly, some into germ-cells, 

 others into follicle-cells. Paulckk (1900) in Apis mellißca and 

 LowNE(1890) in CaUiphora erifthrocephala also observed the filament- 

 cells developing into germ-cells. On the other side. Wielowiejsky 

 (1886) in Feriplanefa, GrijUotalpa and Formica found the end-filament 

 se])arated from the germinal area by a connective tissue partitu)n 

 and. therefore, concluded that the cells were not destined to form 



