STUDIES ON GERM CELLS 503 
Protoplasmic bridges between the cells of Metazoa are not 
uncommon and may exist in all tissues. As a rule, they are 
delicate strands which pass through pores in the cell walls. The 
cellular elements in a syncytium, such as occurs during the 
cleavage of the insect egg, must be even more closely united 
physiologically, since here the cytoplasm forms a continuous 
network. Cellular bridges similar to those described above 
in the queen bee, have been observed in the germ glands of a 
number of other animals, especially insects,, but mostly dur- 
ing spermatogenesis. Thus Platner (’86) found in Lepidoptera 
that often two neighboring spermatocytes, and sometimes 
three, were connected by intercellular ligaments which were 
attached to an intracytoplasmic body in each cell. The latter 
were considered ‘Nebenkerne.’ Similar conditions were dis- 
covered by Prenant (’88), Zimmerman (’91) and Lee (’95) 
in the male germ cells of Gastropoda. Lee, in his work on 
Helix, recognized the true origin of the intercellular bridges and 
their significance. They were found to be the remains of the 
spindle fibers following a mitotic division. The term ‘pont 
fusorial’ was applied by Lee to the bridge itself and ‘moignons 
fusoriaux’ to the ramification of the fibers within the cytoplasm 
of the cells. Similar intercellular ligaments were observed by 
Henneguy (’96) in the seminal cells of Caloptenus; by Erlanger 
(96, ’97) in both the testes and ovaries of the earthworm; by 
Wagner (’96) in the male germ cells of spiders; by Meves (’97) 
in both the testes and ovaries of the salamander; by Giardina 
(01), Debaisieux (’09) and Giinthert (’10) in the ovaries of Dytis- 
cus; by Marshall (’07) in the ovarioles of Polistes; by Kern (’12) 
in the ovarioles of Carabus; by Govaerts (’13) in the ovarioles 
of Carabus and Cicindela; by Maziarski (’13) in the ovarioles of 
Vespa; and by Hegner (14 a) in the testes of Leptinotarsa. 
By far the most interesting results are those obtained by 
Giardina and confirmed by Debaisieux (’09) and Giinthert (710). 
Giardina proved conclusively that a single oogonium in the ovary 
of Dytiscus undergoes four divisions, thus producing sixteen 
cells, one of which is the oocyte and the remaining fifteen nurse 
cells. The processes of differentiation in this genus are partic- 
