KEIMBAHN-DETERMINANTS Q17 
The writer can only conclude (1) that the metanu- 
cleoli differ in nature from ordinary plasmosomes, 
chromatin-nucleoli, and double-nucleoli; (2) that 
these bodies are definitely segregated in a certain part 
of the egg or in a certain blastomere, probably by 
protoplasmic movements; (3) and that their disin- 
tegration and the distribution of the resulting frag- 
ments or granules are controlled by reactions between 
them and the substances in which they are embedded. 
Curomatin. In two genera of animals the differ- 
entiation of the primordial germ cells is accompanied 
by a diminution of the chromatin in the nuclei of 
the somatic cells, so that eventually the nucleus of 
every germ cell is provided with the full complement 
of chromatin, whereas the nucleus of every somatic 
cell lacks a considerable portion of this substance, 
which remains behind in the cytoplasm when the 
daughter nuclei are reconstituted. These two genera 
are Ascaris and Miastor. This diminution process 
was described by Boveri (1892) in the former and 
confirmed by O. Meyer (1895) and Bonnevie (1902), 
and by Kahle (1908) in Miastor and confirmed by 
Hegner (1912, 1914a). For details of these processes 
reference should be made to Figs. 15-16, 51-52, and 
pp. 57 and 174. It may be pointed out here that 
although the final results are similar the process differs 
in the two genera. In Ascaris both ends of each 
chromosome are split off, whereas in Miastor approxi- 
mately one-half of each daughter chromosome is left 
behind to form the ‘‘Chromosomenmittelplatte”’ 
(Fig. 16) and later the “Chromatinreste” (Fig. 18). 
