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smärre uppsatser och meddelanden
177
toluene or chloroform. The dissolving of the chromatin may be duc to
intracellulär enzymes or il may he a simple dissolution wi thou t a chemical
break-down of this kind. Il has recently hcen demoustrated that the chromatin can
he easilv dissolved in simple säll solutions (Mirskv and Pollister, Journ.
Gener. Pliysiol. 30: 101 148, 1946) and even in distilled water
(Gopal-Ayengar and Cowdrv, Cancer Research 7: 1—8, 1947, p. 3).
R e s ii 1 t s. The actively niobile component of the centromere at mitosis
is divided into two parts (»spindle spherules») corresponding to the two
chromatids not only at metaphase hut even in early prophase. The two
cliaracteristic properties of the centromere, that of active mobility and that
of remainiiig undivided until the end of metaphase, must consequently be
carried bv different material components. Furthermore, a close scrutiny of the
spindle spherules, especially those demoustrated bv the second of my two
melliods, shows that eacli of them is in reality double, having an internal
split transverse to the longitudinal direction of the chromosome. That is, each
of the two spindle spherules of a chromosome seems to be composed of two
halves corresponding to the innermost parts of the chromatid arms. This
opinion has been further strengthened by the observation of a doubleness in
the chromosomal spindle fibre bundle attached to the centromere, such as it
appears after ordinary chrome-acetic-formalin fixation and acetocarmine
staining. Thus, I think that the component of active mobility is not the most
central part of the centromere hut that it is the proximal heterochromatin or
»prochromosomic heterochromatin» as it is called by Levan (Hereditas 32:
449—468, 1946). At meiosis the longitudinal split inside this motoric apparatus
(corresponding to the division in chromatids) is probably hut litt le developed
(löw degree of centromere »polarization») and the chief doubleness in the
motoric mechanism of univalents may t hen be that caused by the transverse
gap. This may lead to an orientation ön the spindle perpendicular to the
normal mitotic one and to a transverse division of the centromere, i.e. to the
phenomenon known as misdivision.
Institute of Genetics, University of Lund, Lund, Sweden.
Gunnar östergren.
Ny lokal för Lactuca tatarica (L.) C. A. Meyer på Gotland.
I Svensk Botanisk Tidskrift årg. 1936, har Harald Lindberg skrivit om
förekomsten av Lactuca tatarica (L.) C. A. Meyer i Norden. Han omtalar att
arten sannolikt är stadd i utbredning väster ut i Europa och nämner från
Sverige en lokal, den sandiga stranden invid Närshamn på Gotlands ostkust.
Denna fyndort har senare uppmärksammats bl.a. av MüNTZING (Bot. Notiser
1945).
Sommaren 1946 påträffade undertecknad arten norr om Ljugarn i Ardre
socken på Gotland. Denna lokal är också belägen på ostkusten, c:a 15 km norr
om Närshamnslokalen. Den förekom där på en räll läng sträcka i ett
hundratal exemplar och utgjorde med sina blåvioletta blommor ett färggrant inslag
pa den ensligt belägna sandstranden.
Visby den 15/s 1947. Gustav Åkerblom.
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