No. 466.] STUDIES ON PLANT CELL.— VIII. 793 
of Vejdovsky (: 04) describes and figures a simple type of spindle 
in. Bacterium gammeri and Bryodrilus ehlersi with a separation 
of two groups of chromatin granules during mitosis. 
The chief critics of the conclusions that the cells of Schizo- 
mycetes are nucleated have been Migula (’95) and Fischer. 
The latter author in particular has devoted considerable attention 
to the group especially in his paper of 1897 which is largely a 
discussion of Bütschli's ('96) results on studies of the blue-green 
algae and bacteria. Fischer considers the central body described 
.by Bütschli in the sulphur bacteria as merely a vacuolate region 
of the cell made conspicuous by the arrangement of the sulphur 
grains and that the structure does not appear in cells which are 
free from sulphur. The granular material, considered as chro- 
matin by others, is regarded. by Fischer as reserve material. 
The central body described by Bütschli in the cells of Spirillum 
is stated to be a product of contraction. In general the same 
criticism which Fischer applied to the methods of staining and 
interpretation of structures in the Cyanophycez is presented for 
the Schizomycetes. Fischer cannot justify Bütschli's ('90) view _ 
that the smaller bacteria are chiefly composed of nuclear sub- 
stance, a view which probably has few if any followers to-day 
and could scarcely claim to be more than a passing suggestion. 
In short, Fischer finds no evidence of a nuclear structure in the 
Schizomycetes but curiously ends by declaring that the group 
has no affinities with the Cyanophycez but that its forms are 
closely associated with the Flagellata. 
Saccharomycetes (Yeasts).— The structure of the yeast cell 
has been perhaps the subject of as long a series of investigations 
as the cells of the Cyanophycez and Schizomycetes, and the 
problems in both cases have many similar features. The chief 
problem in the yeasts has concerned the presence or absence of 
an organized nucleus or its equivalent in the form of some sim- 
pler structure. The accounts range from a complete denial of 
its presence to descriptions of a nuclear apparatus of considera- 
ble complexity which passes through some rather involved activi- 
ties during cell division. It is impossible for us to treat the 
subject historically. We shall only consider the accounts of the 
most recent investigators and try to determine the probable 
