


LOTSY, CURRENT THEORIES OF EVOLUTION. 401 
those characters of the mother, which are caused by the 21 singles, 
which are derived from that mother only, they therefore are segre- 
gating hybrids, which all have some maternal characters in common. 
Nor are the Rosae the only kind of not purely mendelian hybrids. 
Among the Oenotherae van OVEREEM has brought to light the 
peculiar fact that semzgigas-forms, triploid forms, can simulate 
mendelian segregation to an astonishing degree, and I can fully 
confirm this from my own cultures. The explanation is the fol- 
lowing. These triploids which posses 21 chromosomes distribute 
their chromosomes during the reduction-division in the makrospore 
; ; HARAS Piet naald 
mothercells in one of the four following ways: T° 8° 9: 10 

so that eggcells with 7, 8, 9, 10, 11, 12, 13 and 14 chromosomes 
are formed, all of which are viable; the reduction division in the 
mikrospore mothercells takes place in the same way, but only those 
pollengrains which contain either 7 or 14 chromosomes are able 
to cause fertilisation. p 
The children consequently form a motley crowd, due to their 
different chromosome numbers, depending on the kinds of eggcells 
and the kinds of pollen combining with one another, as the fol- 
lowing tabulation shows: 
eggcels pollen somatic cells 
of child 
Te TARN TA 
fo Reta, rane 15 
Opt ig ten STG 
TOE PET 
N =o 18 
[ove RE 19 
Ta ST E50 
N ee] 
ee 
TE Nr 
DE | ene 73 
ees hy eed aay 
LEE Sy 25 
ieee Ac 26 
Foe a Aas 27 
ers SS 28 
Genetica. 26 
