The individuality of the chromosomes and their serial aiTangement, etc. 129 
beadlike bodies, and the serial arrangement can be traced in pari These 
chroniatin bodies are certainly not raore numerous than the haploid 
number of chromosomes. 
Meanwhile the three microspore nuclei which were crowded into the 
apex of the old mother-ceU have disintegrated. Juel considers that in 
Carex acuta these three nuclei after forming spindles for dmsion fall 
to complete the mitosis and retmm to a resting stage. I have not been 
concerned especiaUy with this point, but my preparations indicate that 
there is more or less irregiüarity in the division of these three nuclei, 
and that as a result froni three to six nuclei may be found at the apex. 
Juel, as I judge, shows five nuclei in this position in one of his drawings 
(Juel 1900, fig. 42). At first plasma membranes mark the boundaries of 
these ceUs (fig. 33). Later they become shriveled into compact masses 
which are closely pressed into the apex of the mother-cell wall. The 
central cytoplasmic mass is separated from these degenerating nuclei 
by a plasma membrane. 
The matiu'e pollen grain consists of a large vegetative cell in the 
cytoplasm of which are two gerni cells each ^vith a clearly defined plasma 
membrane. The wall of the old spore mother cell evidently becomes a 
part of the wall of the mature pollen grain. 
Discussion. 
It is evident from the above account that in Carex aquatilis the 
chromosomes can be observed as unit masses at all stages of nuclear 
development, except during synapsis and the thick spireni stage which 
foUows it. The an'angement of these units in series is also a conspicuous 
and rather uniform featiue. 
The eai'her evidence supporting the doctrine of the iudmduality 
of the chromosomes has been quite fully summarized by Boveri (1904). 
The evidence is based largely (1) on the uniformity in the number and 
character of the chromosomes appearing in successive divisions, (2) on 
the proof that whenever more or less than the usual number of chromo- 
somes enter a nucleus in the eggs of Ascaris the same number always 
appears in later di\isions of that nucleus, (3) on the evidence that the 
loss of chromosome identity during the reticulatcd condition is only 
, (4) on the proof that nuclear fusion doubles the number of 
»mes while the reduction dmsion decreases the number by 
lirdf. Boveri extended the conception of individuality to the extent of 
Tegarding the chromosomes as elementary organisms rather than merely 
permanent ceU organs. 
Archiv f. Zellforschung. IX. 
apparr^nt 
chroinoso 
9 
