298 
MONICA TAYLOR. 
of homologous chromosomes to fuse into an apparently 
single chromosome. This would entail a study of rafts 
ranging from a quarter hour to three and a half to four days 
old. (The development of the larva in Scotland occupies 
from three and a half to four days.) Moreover, the egg- 
capsule becomes so hard and brittle as it changes from cream 
white to dark brown, that a special technique would have to 
be devised for sectioning these eggs without destroying the 
nuclear detail. All that can be stated with certainty up to 
the present is. that the homologous chromosomes have not 
fused in segmenting nuclei — while this fused condition has 
become a characteristic of Culex pipiens in the early larval 
stage. 
It would seem, then, that parasyndesis has reached its limit 
in the somatic tissues of Culex pipiens, resulting in the 
actual fusion of homologous chromosomes, and that extreme 
parasyndesis is responsible for the apparent anomaly de- 
scribed in the f Chromosomes Complex of Culex pipiens', I. 
General. 
There is general agreement that we are justified in 
assuming (1) that hereditary qualities are represented by 
material substance, and (2) that this substance is either 
chromatin or is inextricably involved in chromatin. Granting 
these two assumptions, we seem logically bound, by the 
generally occurring accurate longitudinal splitting of the 
chromosomes in mitosis, to admit that the patches of material 
representing definite hereditary qualities are arranged in 
linear fashion along the course of the chromosome or thread 
of chromatin. But this involves necessarily a tendency of 
the hereditary substance representing one particular quality, 
or group of qualities, to segregate together. In other words, 
there must be, in the case of hereditary substance, an 
attraction of like for like. If this be so, there will be a 
tendency for chromosomes composed of corresponding patches 
of hereditary material arranged in like order, to come 
