Nuclear Divisi and Development of Sterigmata in Coprinus atramentarius

Abstract

1. After fusion of the two nuclei in the basidial cell of Coprinus atramentarius, synapsis takes place in the single nucleus. This nucleus then migrates to the apex of the cell and its membrane comes in contact with the cell wall, where four hyaline bodies become attached. With the withdrawal of the nucleus to the center of the cell cytoplasmic threads are drawn out. These connect the hyaline bodies left on the wall to the nucleus. 2. The centrosomes of the spindles are not interfered with in the formation of the four hyaline bodies which remain on the basidial wall. After the first division, threads from four hyaline bodies are attached to the two nuclei; after the second division, threads from four hyaline bodies are attached to as many nuclei. 3. The long axis of the spindle has no definite orientation in either division. 4. The hyaline bodies remain attached to the apex of the cell wall from the time the fusion nucleus comes in contact with it until after formation of the spores. These bodies react on both the wall and the nucleus in such a way that the wall pushes up at their points of contact and sterigmata form. The nucleus then follows, and after it has entered the spore the wall greatly enlarges and assumes mature proportions. 5. After the hyaline bodies become attached they remain at all times at the apex. After a sterigma forms a hyaline body is at the tip as well as after the spore is formed. 6. There are eight chromosomes in the fusion nucleus. Reduction takes place in the first division.