Contributions to the Cytology of Fungi

II. Cytological Studies in Morchella deliciosa Fr.

Abstract

1. The Young ascus is binueleate in the primary stage. After the fusion of the two nuclei, meiosis occurs.
2. The first division is heterotypic, and a typical synaptic knot with a large nucleolus is cleary observed.
3. The meiotic spindle is of intranuclear origin, and at each pole of it is seen a centrosome with well developed astral rays.
4. The behaviour of chromosomes in separation in the anaphase is more or less irregular.
5. The second division is homotypic, giving rise to four daughter nuclei.
6. In the third division, there are clear indications of the oc-curence of the so-called “brachymeiosis”, as far as the numerical diminution of chromosomes occurs, but the writer reserves to decide whether the latter represents a true reduction in its ordinary sense or not, until a further investigation of the fusion-modus is made. Accordingly, the number of chromosomes in meiotic division in Morchella deliciosa is reported for the present as 12.
7. In exceptional Gases, tetraploid asci were met with, and the mitotic spindle of intranuclear origin with about 48 univalents was found.
8. After the third division, eight daughter-nuclei with intensively radiating astral rays are formed; radiations proceed until the astral rays meet at the opposite pole, sweeping round the nucleus and finally delimiting the spore by the formation of a spore membrane.
9. A typical mitosis takes place in the spore, 6 chromosomes being observed in the telophasic nuclei, so that the spore becomes binucleate.