Quarterly Journal of Microscopical Science, Vol s2-73, 225-242, Copyright © 1929 by Company of Biologists

Memoirs: The Early Prophases of the First Oocyte Division as Seen in Life, in Obelia Geniculata

¹ Demonstrator in Zoology in Bedford College, University of London

1. The nueleolus of the resting oocyte represents a condensed chromatic spireme, hence it is identical with the total chromosomal contents of the nucleus.

2. During the early growth phases of the oocytes, the nueleolus elongates and fragments. Each fragment has been identified as a pair of homologous chromosomes indistinguishably united; later each of these bivalent elements divides in half, and the individual chromosomes are thus separated. The two components of the largest bivalent element are unequal in size, and probably represent an XY pair.

3. The chromosomes can be counted either at the bivalent or at the univalent phase, the numbers obtained being seventeen and thirty-four respectively.

4. At a still later stage the chromosomes fragment into numerous small globules, which become evenly distributed over the nucleus.

5. The whole of the account is based on observations made on living oocytes.