282 Kobert Wilhelm Hegner. 



perfectly fixed pole-cells, and I conclude that Lecaillon was deceived 

 by the irregular outline of the '^cellules sexuelles," and tliat in Clytra 

 the apparent distortion of these cells was due, not to poor fixation, 

 but to their amoeboid character. 



Several authors have described the locomotion of primitive germ- 

 cells in other orders of insects. Ayers (1883) states that the germ- 

 glands of Oecanthus "are first seen as two irregular groups of 

 amoeboid cells." In Forficiila (Heymons, 1895) the germ-cells arise 

 near the posterior end of the egg >and migrate anteriorly. "Die 

 Bewegung diirfte hierbei durch Aussenden amoboider Fortsiitze 

 erfolgen, die man jetzt an den Zellen gar nicht selten beobachten 

 kann." 



Heymons (1895) says of Periplaneta, ''Aehnlich wie in gewissen 

 Stadien von Forficula scheint die Fortbewegungsart der Zellen hier- 

 bei eine amoboide zu sein, es kann dies wenigstens aus den zahl- 

 reichen Gestaltsveranderungen der Geschlechtszellen geschlossen 

 werden, die bald rundlich, bald langgestreckt sind oder lappige 

 Fortsiitze aussenden." 



The pole-cells of both Calligrapha and Leptinotarsa not only 

 migrate by their own activity, but their movements are distinctly 

 amoeboid. It has been noted above that every preblastodermic nucleus 

 has long cytoplasmic processes extending out on all sides into the 

 yolk. It has also been shown that these processes become blunt in 

 the case of the pole-cells when separation from the egg takes place 

 (Fig. 22). If we examine the pole-cells from the time they are 

 protruded until they become aggregated into a distinct germ-gland, 

 we discover a series of stages which establish their amoeboid character 

 as well as it is possible to do in fixed material. 



During their protrusion, the pole-cells have still an irregular 

 outline, but their cytoplasmic processes are no longer present on 

 their outer surface ; this is probably due to being pressed against 

 the "Keimhautblastem" (Figs. 20 and 21). After complete separa- 

 tion, however, they again acquire an amoeboid shape, their blunt 

 psevidopodia containing most of the granules taken from the pole- 

 disc (Fig. 22). This appearance is retained until the pole-cells 

 begin to migrate through the pole-cell oanal; then the pseudopodia 



