44 Overton . — On the Organization of the Nuclei in the 
parents, as a result of the apparent persistence of the chromosomes as 
individuals from one generation to another. The final behaviour of the 
chromosomes during maturation of the germ cells, though they are not as 
numerous as the Mendelian characters are generally assumed to be, never- 
theless, on the basis of the facts of symixis can be brought into accord with 
the Mendelian principles of heredity. 
Although the earlier students of fertilization observed what was an 
apparent complete fusion of the germ nuclei, later workers have shown that 
in normal development fusion of the germ nuclei involves no fusion of the 
homologous parental chromosomes. Van Beneden (’83) showed that the 
germ nuclei of Ascaris give rise to two individual groups of chromosomes 
whose halves pass independently into the daughter nuclei. Riickert (’95) 
and Haecker (’96, ’02) have shown that in Cyclops the parental chromosomes 
do not mingle, but persist as individuals and retain their parental grouping 
through several cell generations, possibly persisting through the entire life- 
cycle, which Conklin (’02) has shown to probably obtain in Cripidula. 
Haecker (’02, ’07), as a result of his and Riickert’s (’95) studies in Cyclops , 
maintains that the more important parental nuclear substances do not com- 
mingle but remain distinct until the prophases of the first division, when 
the conjugation of the parental chromosomes occurs. Haecker (’07) has 
recently further developed his conception of the autonomy or the separate 
existence of the paternal and maternal nuclear parts (‘ gonomeres ’), believing 
that this independence of the gonomeres is general in sexually produced 
animals and plants. 
Haecker (’02) further maintains that the nuclei show their double 
nature by the presence of two nucleoles and two spirems, as well as by 
their two-parted or two-lobed form. Boveri (’04), however, points out that 
it is not essential in view of the theory of chromosome individuality, whether 
the parental nuclear portions have a spacial separation or not. The work 
of Moenkhaus (’04), however, on hybrid fishes, in which the parental 
chromosomes are of different sizes, points to a final commingling of the 
chromosomes, although they retain their individuality and the nuclei keep 
their two-lobed form with a single nucleole in each lobe. 
The investigations of Blackman (’04) and his students, and of 
Christman (’05) on the rusts, show that the parental nuclei may remain 
perfectly distinct in the same cell for the entire period of the sporophyte. 
Hamburger (’04) maintains that the nuclei of conjugating Paramaecia do 
not entirely fuse. 
Blackman (’98), Chamberlain (’99), and especially Miss Ferguson (’04), 
have furnished evidence that the maternal and paternal chromatins remain 
distinct during fertilization, observing that during the first division of the 
fertilized egg-cell of Finns, the parental chromatins form two separate 
spirems. Similar results have also been reported by Murrill (’00), in Tsnga , 
