May, 1913.] 
A Cycological Life Cycle. 
145 
ing would have borne the same chromosome combination as their 
parents. The combination diagramed could never be repeated 
until egg and sperm containing between them the chromosomes 
represented by all four symbols met and in the resulting zygote 
the chromosomes were oriented on the spindle in exactly the 
proper manner and this was followed by a succeeding fertilization 
by pure gametes bearing respectively only dotted and crossed 
chromosomes. Thus in an organism with four chromosomes in 
the diploid generation there are no less than nine possible chromo¬ 
some combinations, while in organisms with numerous chro¬ 
mosomes the number of combinations possible is 3" where n is the 
number of chromosomes. 
Without making any specific assumptions concerning dif¬ 
ferences in specific maternal and paternal chromosomes other 
than the common knowledge that the plasms of the two parents are 
in a general way different in heterozygous organisms, it is evident 
that there is here a mechanism varied enough to account in large 
measure for the large variability in inheritance which is so familiar 
No two children of the same parents (except identical twins) are 
ever alike, be the family ever so large. When we take account of 
intermarriage even without considering varying racial char¬ 
acteristics it is not surprising that we never find two faces alike. 
If however we assume that the long crossed chromosome for 
example bears a specific character which is absent from its mate 
the long dotted chromosome, it will be seen that any one of four 
possible combinations with respect to this one chromosome and 
the character it bears may be realized in fertilization: (1). An 
egg bearing the x chromosome may be fertilized by a sperm 
bearing an x chromosome or, (2), by a sperm bearing a dotted 
chromosome, (3), an egg bearing a dotted chromosome may be 
fertilized by a sperm bearing an x chromosome or (4), by a sperm 
bearing a dotted chromosome. In the first case all of the cells 
produced in the subsequent reduction would bear the x chromo¬ 
some together with its character, and if inbred would continue 
pure ever after. In the fourth case the offspring would be pure 
in respect to the dotted chromosome and whatever characters 
it might carry, while in the second and third cases it would be 
mixed. This is, however, nothing more or less than a statement 
of Mendel’s Law. 
