20 LOTSY, CUCURBITA-STRIJDVRAGEN. 
6. Reciproke kruisingen tusschen C. Pepo en C. aurantiaca 
toonen eenige verschillen in vrucht-lengte en vrucht-grootte en zijn 
in beide gevallen matroklien. Absolute zekerheid, dat dit verschil 
niet op heterozygotie der gebruikte vormen berust, kon nog niet 
worden verkregen, hoewel deze, juist door de matroklinie in beide 
reciproke kruisingen, zeer onwaarschijnlijk is. 
7. De door mij onderzochte vormen van Cucurbita zijn niet tot 
_apogame of parthenogenetische ontwikkeling in staat; de door de 
HAGEDOORNS als parthenogenese beschreven gevallen zijn waar- 
schijnlijk gevallen van ongewilde bestuiving door insecten ten- 
gevolge van onvoldoende isolatie. 
8. Sommige mijner vormen zijn parthenocarp d.w.z. in staat 
zaadlooze vruchten zonder bestuiving te vormen. 
Résumé. 
1. Several, often very different, constant forms (Jordanons) could 
be distinguished within the Linneon Cucurbita maxima as well as 
within the Linneon Cucurbita Pepo in the sense of NAUDIN. 
2. Jordanons, belonging to the same Linneon, cross easily and 
give fertile segregating hybrids. 
3. As yet crosses between Jordanons belonging to different 
Linneons have had no results in my experiments. 
4, Considering the very large number of unsuccesfull efforts it 
seems pretty safe to say that neither C. Pepo nor C. maxima can 
be crossed with C. melanosperma, an equally strong opinion can 
not yet be given as to the possibility of crosses between C. Pepo 
and C. maxima; those tried were unsuccesfull, but the number-of 
efforts was much less than in the case of crossings between C. 
Pepo or C. maxima with C. melanosperma. 
5. Crosses between C. Pepo and C. aurantiaca Willd. are as fertile 
and segregate as fully as those between Jordanons belonging to 
the same Linneon, it should however he remembered that NAUDIN 
considers C. aurantiaca as a mere — though very definite — 
variety of C. Pepo. 
6. Reciprocal crosses between C. Pepo and C. aurantiaca show 
certain differences in the length and size of the fruits, these being 
in both cases matroklinal. Absolute certainty, that these differences 
are not due to heterozygotism of the forms crossed was not 
