- 
al 
Nachdruck verboten. 
Studies on Germ Cells.t) 
III. The Origin of the Keimbahn-Determinants in a Parasitic 
Hymenopteron, Copidosoma.?) 
By Rosert W. HEsNeERr. 
With 18 Figures. 
From the Zoological Laboratory of the University of Michigan, Ann Arbor, 
Michigan, U.S.A. 
Introduction. 
In another place (Hrsxer, '14) the writer has pointed out that 
in almost every case where an early segregation of germ cells has 
been demonstrated in the development of animals a peculiar inclusion 
appears in the cytoplasm of the egg at or near the time of maturation. 
This body finds its way into the primordial germ cell or cells, breaks 
up into granules, and becomes distributed among the descendants of 
the primordial germ cells. ‘These inclusions enable us to determine 
with accuracy the germ track during embryological development 
and have hence been termed keimbahn-determinants. Thus far keim- 
bahn-determinants have been most accurately described in insects, 
Crustacea, and Sagitta. Those of Sagitta were discovered by Er- 
PATIEWSKY (’09, ’10) and termed the ‘besondere Körper’; they were 
further studied by Srevens (10) and Buchner (710a, 10b). Among 
the Crustacea certain Copepoda and Cladocera exhibit distinct keim- 
bahn-determinants. Haxcker (97) described them as * Aussenkörn- 
chen’ in Cyclops, and Amma (’11) has found them in a number of 
other copepods. Similarly Kunw (’11, ’13) has reported their presence 
in Cladocera. Keimbahn-determinants occur in certain species belong- 
ing to three orders of insects, the Diptera, Coleoptera, and Hymenoptera. 
They are best known among the Diptera in Chironomus as the ‘ Keim- 

1) Parts I and II of this series of contributions on germ cells are to 
appear in the Journal of Morphology for June, 1914. 
2) Contributions from the Zoological Laboratory of the University of 
Michigan, Ann Arbor, Michigan, U.S.A., number 888. 
4* 
