The Germ-cells of Lophius. 593 



are now known to have similar processes. Kahle ('08) describes 

 a process of a somewhat similar nature in the development of 

 gall-gnats (Cecidomyidae). At the 8-cell stage the cell with the 

 undiminished amount of chromatin is the first germ-cell. Giar- 

 dina ('01) and Debaisieux ('09) described in the beetle, Dytiscus, a 

 loss of nuclear material during oogenesis. A single indifferent cell 

 of the egg tube undergoes four divisions, during the first of which 

 but half of the nucleus enters into the formation of the mitotic 

 figure. The remaining half forms a separate mass which passes 

 down entire to a single cell which at the fourth cleavage becomes 

 a germ-cell, while the other fifteen daughter cells lacking this 

 body are the follicle cells. 



In the preceding cases it is the chromatin of the nucleus that 

 is involved, while in others now to be described, the early nuclear 

 changes have to do especially with the plasmosomes. Hacker 

 ('97) found that in Cyclops during each of the first nine cleavages 

 there is an emigration of plasmosome material from the nucleus 

 of a single blastomere into the cytoplasm, where it disappears 

 during the telophase. At the ninth cleavage this blastomere is 

 the first germ-cell . The same writer ('92) described in the medusa, 

 Aequorea, the extrusion of a plasmosome from the nucleus at 

 about the time of the first maturation; this persists undivided in 

 the cytoplasm up to the 64-cell stage; he did not trace the fate of 

 this cell, but it seems probable in the light of other cases that this 

 body may mark the first germ-cell. Silvestri ('06) found that 

 in the parasitic wasp, Lithomastix truncatellus, the plasmosome 

 is transmitted entire through the first two divisions to a single 

 blastomere of the 4-cell stage. Tt is also probable that in this 

 case this cell represents the beginning of the germ-cell line. 



Elpatiewsky ('09) found that in Sagitta the first germ-cell is 

 marked at the fifth cleavage by the presence in the cytoplasm of 

 a 'besonder Korper' which has come down entire from the begin- 

 ning of cleavage. He did not trace its origin but considered that 

 probably it is nuclear. Buchner ('10) however, who later studied 

 this point, considered that the bod> is the persisting chromatin of 

 an ingested follicle cell. Hegner ('09) described the differentia- 

 tion of the germ-cells of some Chrysomehd beetles as beginning 



