Special M orphology and Classification. 261 
at least at the commencement of the attack and possibly as its cause, 
enormous quantities of organisms, the identity of which with Zoog/aa 
Tei mo, or their difference from it as a separate organism under the 
name Z. cholere (Fig. 391 Iv.), has not yet been determined. Under 
the Schizomycetes must also be included Leptothrix buccalts (Fig. 391 
I1.), an organism which always occurs in the mouth, especially in the 
mornirg, but is in general without significance as a morbificant. 
It consists of extremely delicate transparent filaments, which, neverthe- 
less, appear to be composed of separate cells, since they break up into 
sharply defined pieces simply on being touched. To this class belongs 
also the substance knewn as Monas prodigiosa, closely resembling the 
red corpuscles of the blood, which sometimes appears in prodigious 
quantities on bread and similar substances. 
[As Protococcus is one of the types of organic life to 
which, special attention is called in the new syllabus for. 
the science examinations at the University of London, a 
somewhat more detailed account may be given of what is at 
present known respecting it. It is found very abundantly 
in the mud where rain-water collects, and 1n similar situations. 
In its most ordinary form, each individual consists of a — 
single, nearly spheroidal, cell from ‘oo3 to ‘oooor inch in _ 
diameter ; and varying in colour from bright green to bright . 
red, according to the relative proportion of a green and a 
red colouring matter diffused throughout the protoplasm, or 
occurring in the form of granules. In this form it multiplies 
with great rapidity by fission, z.e. by simple cell-division ; 
and is also stated occasionally to increase by gemmation 
or budding. The individual Protococcus performs all the 
functions of an ordinary vegetable cell, respiring, ze. 
absorbing oxygen and giving off carbon dioxide in the — 
dark, in consequence of the oxidation of its substance, 
and probably also in the daytime, although the process is 
then concealed by the opposite process of nutrition, or the 
decomposition of carbon dioxide and elimination of oxygen, 
which is effected by the chlorophyll under the influence of 
sunlight. ‘The change to the active condition takes place in 
the following way. The protoplasm withdraws itself from 
