On the Nature of Fertilization and Se*. 
177 
At fertilization the protoplasts of the male and female 
partners unite to form the zygote and at the same time the 
number of chromosomes, etc., becomes doubled . 1 At some 
subsequent stage of development the number of chromosomes 
becomes halved owing to the occurrence of a “ reduction division,” 
but there seems no reason why this should necessarily involve a 
separation of the “ active ” and “ passive ” elements of which the 
organism is built up. 
To state the matter more explicitly, it is not suggested that 
the “ active ” and “ passive ” types of protoplasm, which, as 
partners, build up the zygote, are homologous with the Mendelian 
factor-carriers or with the two sets of chromosomes, but rather that 
they form a mosaic groundwork within which the latter more 
definite bodies occur . 2 
An analogy, even though somewhat crude, may help to make 
the conception clearer. 
Suppose the “active” and “passive” types of protoplasm to be 
represented by alcohol and water and the two sets of chromosomes 
by iron and brass filings suspended in these liquids. If we mix the 
two suspensions there results an intimate mixture of alcohol and 
water and a mixture of iron and brass filings. By the use of a 
magnet it would be easy to separate the fluid into two portions, 
one containing iron filings and one brass filings. This would 
correspond to the segregation of chromosomes that occurs at the 
reduction division. The operation would not necessarily involve 
the separation of the alcohol from the water. For this, other 
forces, such as those employed in the process of distillation would 
be required. 
Thus, although the same act of mixture was responsible for 
bringing about the double nature both of the fluid and of the 
filings, the process causing the separation of the filings does not 
1 Doubled, if there are the same number of chromosomes in male and 
female gametes. 
* The duality of the organism, as regards the number of chromosomes, 
ceases at the “ reduction division” characteristic of meiosis, which occurs at 
some definite stage in the life history. The duality in respect to hereditary 
characters is brought to an end, normally, at the same time (wherefore the 
supposition that such characters are carried by the chromosomes). But never¬ 
theless the character factors would appear to be independent to some extent of 
meiosis in view of the occurence of phenomena such as somatic segregation and 
reduplication. Lastly, as suggested below, the separation of the protoplasmic 
partners is independent of either of the above segregations, and although 
occurring some time before the formation of gametes, may take place at 
different stages in the life cycle, according to the nature of the organism. 
