176 Trow . — Observations on the Biotogy and 
for as long a period as four months. The single nucleus 
undergoes indirect divisions, and the number of chromosomes 
which appear during these seems to be eight. About twenty 
nuclei are produced by successive divisions. One or more 
germ-tubes are produced, and at the apex of each a small 
sporangium with from four to ten zoospores. A direct 
formation of a small mycelium from a germ-tube sometimes 
takes place. 
9. A consideration of the chief facts of karyology, especially 
in the Thallophytes and in their relation to apogamy, leads 
to the conclusion that reducing-divisions in the different 
groups of plants are not all homologous. There is a true 
homology in the Muscineae, Vascular Cryptogams, and Sper- 
maphytes. In the Thallophytes there are apparently two 
types of reducing-division which are not homologous. 
University College, Cardiff, 
A r ovember, 1898 . 
