108 GERM-CELL CYCLE IN ANIMALS 
We owe the first accurate account of the germ 
cells in Chironomus to Ritter (1890), who, by means 
of the section method, showed that the “yolk 
granules” described by Weismann (1863) in the 
pole cells are derived from a disc-shaped mass of 
substance situated near the posterior end of the egg 
and termed by him the ‘“Keimwulst.”’ Hasper 
(1911) was able to confirm this discovery, to add 
other interesting facts, and to correct several of 
Ritter’s errors. The “Keimwulst” of Ritter is 
called by Hasper the “‘ Keimbahnplasma.”’ 
Ritter advanced the idea that the cleavage 
nucleus of Chironomus divides within the “Keim- 
wulst”’ and that here the first cleavage division 
occurs, one daughter nucleus remaining in the “ Keim- 
wulst”? and becoming the center of the primordial 
germ cell, the other giving rise to somatic nuclei. 
This is probably the basis for Weismann’s (1904) 
statement regarding his conception of the germ- 
plasm that, “If we could assume that the ovum, 
just beginning to develop, divides at its first cleavage 
into two cells, one of which gives rise to the whole 
body (soma) and the other only to the germ-cells 
lying in this body, the matter would be theoretically 
simple. ... As yet, however, only one group of 
animals is known to behave demonstrably in this 
manner, the Diptera among insects... .’ There 
is, however, nothing in the literature to warrant 
the above statement, since Ritter’s hypothesis 
has been disproved by Hasper. 
According to Hasper one of the cleavage nuclei 
