324 A CYTOLOGICAL INVESTIGATION OF SOME SPECIES 
origin out of the latter, by mere doubling of chromosomes, impossible. 
He therefore tries to explain the origin of series of chromosomenum- 
bers, such as 8, 16 and 24 in the case of Musa and 9, 18, 27, 36 and 45 
in the case of Chrysanthemum in another way, to wit: by crossing. 
Chromosomes are very frequently inclined to arrange themselves in 
pairs in the somatic cells already, but this tendency shows itself especi- 
ally in the gonotokonts, in which the two chromosomes of a pair are usu- 
ally closely united. If two gametes, which pair during fertilisation, have 
much in common, as in the case of gametes of closely related parents, 
the corresponding male and female chromosomes will form gemini in 
the gonotokonts. In such a case WINGE speaks of philozygosis. 
When the parents are less closely related, it may happen, that there 
is pathozygosis e. g. that a direct pairing of chromosomes is impossible 
but that pairing can take place in an indirect way. In cases of mıso2y- 
gosis the formation of a zygote, in which male and female chromoso- 
mes occur harmoniously, is no longer possible. 
In cases of pathozygosis, WINGE imagines chromosome-pairing pos- 
sible by means a previous splitting of all the chromosomes in the zygo- ~ 
te and the subsequent pairing of the fission-products of each chromo- 
some. This process he calls „indirect chromosome union’ in contra- 
distinction to the direct chromosome-union which takes place when 
each chromosome of the one parent at once finds a partner in one of 
the other parent in the zygote. Direct chromosome union therefore is 
not accompanied by a doubling of the chromosomenumber, indirect 
chromosome union is. 
WINGE supposes, that in cases of indirect chromosome-union in the 
zygote, normally sexual,as well as apogomous, plants can arise from it. 
In the case of normally sexualplants, gametes with the haploid chro- 
mosomenumbers of both parents would be formed after reduction. 
A cross of two species, A and B, each with 9 chromosomes in their 
gametes would give a primary zygote with 9a + 9b chromosomes ; after 
splitting of these chromosomes the zygote, as well as the somatic cells 
“ of the daughter-individual arisen from it, would contain 2 x 9a + 2x 
x 9b chromosomes. The reduction-division would subsequently give 
gametes with 9a + 9b chromosomes, so that the haploid chromosome- 
number of this daughter individual would be 18. A cross of this indivi- 
dual with a species C, also with 9 chromosomes in the gametophyte, 
would give a primary zygote with 9a + 9b + 9c chromosomes; after 

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