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the female gametophyte in nolana
377
Fig. 13. Diagrammatic scheme showing endosperm types and suggested phylogenetic
development. See the text.
The writer has examined Solatium dulcamara, type 1, Brovallia
viscosa, type 3, and Nicandra physaloides, type 3. As to Nicandra in
another case, verv rare in my preparations, type 1 could be noticed.
I conceive that this form, very rare in occurrence, is a primitive and
atavistic phenomenon and because tiie early endosperm in the
Verbas-cum-type has a similar structure I suggest Ibis endosperm type is the
primitive type in Solanaceae. The course of endosperm development in
the family in my opinion is illustrated in Fig. 13. The type I is Ihe
primitive form and type 6 is the most progressive and youngest form.
In Hyoscyamus type 2 may also be an alavistic form and it is of no
small interest or significance that Ihe endosperm has the same structure
as that in Nolana. The types 4 and 5 are clear intermediate forms to
type ß. Bui I am not inclined lo interpret their coming into existence
as does Schnarf (1(5, p. 388): »Dieses variable Verhalten findet dadurch
seine einfachste Erklärung, dass in manchen Fallen die micropvlare
Endospermzelle kleiner, in anderen grosser ausfällt. Im ersteren ist eine
Zellbildung möglich, im letzteren findet nur Kernteilung stall», and
further by his explaining the helobial endosperm (p. 389) »wurden
älmliche trophische und Raumverhällnisse angezogen». If space would
be the determining factor as regards the micropvlar chamber il would
also be valid for the chalazal chamber, but I think Svenssons Figs. 4e
and 4 f (type 2 and 4 above) do not give an impression of any greater
difference existing between the cellular chalazal chamber in 4 f and
the nuclear one in 4 e. Therefore I do not think that the different
endosperm forms are due to space, I think, that on certain occasions the
accumulation of factors or genes responsible for nuclear endosperm
formation has not been sufficient for producing this type and then any
intermediate type (type 4 or 5 above) may be Ihe result.
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