mes a nucleus may be noted. This latter is best
seen when stained with haematoxylin (see page 105).

During their growth and multiplication the blastomycetes split up
solutions containing sugar into alcohol and CO_{2}.

~Saccharomyces~ (Fig. 81).--Note the round or oval cells of granular
protoplasm (a) containing solid particles and vacuoles (c), and
surrounded by a definite envelope.

~Reproduction.~--Budding; ascospores--asexual.

Note the asexual _reproduction_.

1. "Gemmation"--that is, the budding out of daughter cells (b) from
various parts of the gradually enlarging mother cell. These are
eventually cast off and in turn become mother cells and form fresh
groups of buds.

[Illustration: FIG. 81.--Saccharomyces with ascospores.]

[Illustration: FIG. 82.--Torula.]

2. Spore formation--"ascospores" (e). These are formed at definite
temperatures and within well-defined periods; e. g., Saccharomyces
cerevisiae, thirty hours at 25 deg. to 37 deg. C., or ten days at
12 deg. C.

~Torulae~ (Fig. 82).--Torulae, whilst resembling yeasts in almost
every other respect, never form endo-spores. Note the elongated,
sausage-shaped cells (a) the larger oval cells (b) and the globular
cells (c) the former two often interlacing and growing as a film.

Note the absence of ascospore formation.

IX. SCHIZOMYCETES.

~Classification and Morphology.~--Bacteria are often classified, in
general terms, according to their life functions, into--

_Saprogenic_, or putrefactive bacteria;
_Zymogenic_, or fermentative bacteria;
_Pathogenic_, or disease-producing bacteria;

or according to their food requirements into--

_Prototrophic_, requiring no organic food (e. g., nitrifying bacteria);
_Metatrophic_, requiring organic food (e. g., saprophytes
and facultative parasites);
_Paratrophic_, requiring living food (obligate parasites);

or according to their metabolic products into--

_Chromogenic_, or pigment-producing bacteria;
_Photogenic_, or light-producing bacteria;
_Aerogenic_, or gas-producing bacteria;

and so on.

Such broad groupings as these have, however, but little practical value
when applied to the systematic study of the fission fungi.

On the other hand, no really scientific classification of the
schizomycetes has yet been drawn up, and the varying morphological
appearances of the members of the family are still utilised as a basis
for classification, as