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the female gametophyte in nolana
379
above and that at the chalazal part of the endosperm (p. 33):
»Ilaus-torien werden in einem sehr späten Entwickhingsstadium
ausdifferen-ziert». This indicates that the chalazal haustorium is retrograding. In
Phacelia congesta (he haustorium appears after protacted hesitancy, so
lo speak. These Phacelia forms are more reduced lhan that of
Nemo-phila if we moreover consider Iheir lacking micropylar haustoria.
In Phacelia Parryi Ihe endosperm in Ihe beginning is of type 3
above but in each of the four endosperm cells free nuclei are produced.
If one considers the Hyoscyamus-type (type 5 above) producing free
nuclei after the first division, Ihe Parryi-[ype will get free nuclei alter
the second division. This is the real difference between these two lypes.
The Parryi-type is an intermediate form to the nuclear type in Phacelia
tanacetifolia and malvifolia. Svensson quotes (p. 38) that the
endosperm of Phacelia viscida is of type 3 above, but sometimes after the
first division an oblique wall will be formed in Ihe micropylar chamber.
Perhaps a detail of no significance but perhaps il means an atavistic
form, type 2 above, indicating the origin of type 3 above.
In Hydrophyllaceae, too, the most progressive endosperm form is
Ihe nuclear type, which through Ihe Parryi-[ype may be derived from
the congesta and viscida forms, which in their turn may originate from
the Nemophila-type, that is Ihe primitive type in this family and that
most probably may be derived from an endosperm type similar lo that
of Verbascum. The scheme in Fig. 13 above is valid for the endosperm
development in this family, too.
There is no doubt that a similar development has occurred in the
Boraginaceae. Here Heliotropium is Ihe primitive type (type 3 above).
It has a reduced one-nucleale micropylar haustorium while on the olher
hand the chalazal haustorium has disappeared. Borago is the most
progressive type (type <5 above). The endosperm in Myosotis is cellular
(probably type 1 above) and has no haustoria. Some endosperm forms
described by Svensson are interpreted by Schnarf (16, p. 351) as
representing a helobial Ivpe, having a few nuclei in Ihe lateral (basal)
chamber, quite as in Hyoscyamus (type 5 above). Very possible of
course and if that is so, the scheme (Fig. 13) will be applicable also
here. But Svensson wriles (p. 106) that in Nonnea in the lateral
chamber four cells having hypertrofied nuclei come into existence. This can
be interpreted as a poor developed four-cellular chalazal haustorium
and the Lycopsis-lype can be interpreted in the same manner. In Ihis
type a reduction would first have affected Ihe micropylar haustorium,
that led to ils disappearance, Ihe chalazal haustorium still persisting.
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