337 
essential and decisive difference in true cell-nuclei beiug diffe- 
rentiated in the substance of the sarcode in all Protoplasta, 
while this is never the case in the Monera. 
The three remaining groups of Protista, the Phyeochro- 
maceae, Fungi, and Noctiluca?, show less decided relations 
to the Monera than the six groups just considered, and a 
special comparison of them is, therefore, superfluous. But 
the lowest Fungi, as well as the simplest Phycochromacese, 
are immediately allied to the Monera by the simplicity and 
the lower grade of development of their structure and of 
their life-phenomena. Their simplest ancestors may have 
proceeded directly from Monera. 
In any case, it becomes even now perfectly clear from the 
sketch above given, and from a simple comparison of the his- 
tory of the development of the different Protista that, without a 
complete knowledge of their individual development-history, 
these very low organisms cannot at once be referred with even 
approximate certainty to this or that group of Protista. This 
especially and peculiarly applies to all naked Amoeba-like 
and Actynophrys-like bodies, as well as to the Myxomy- 
ccta-like plasmodia, and to the Flagellata-like zoospores. 
Here, as everywhere in morphology, as Baer says, “ the 
history of development is the true Guide-light for investiga- 
tions into organic bodies.” But none the less is the weighty 
proposition also verified here, “ that the theory of descent is 
the true Guide-light for the whole history of development.” 
VI . — Systematic arrangement of the Monera. 
Character of the groups of Monera . — 
Organisms without organs, which in their perfectly developed 
condition form a freely moving, naked, perfectly structureless 
and homogeneous mass of sarcode (Protoplasm). Nuclei are 
never differentiated in the homogeneous protoplasm. Move- 
ment is effected by contraction of the homogeneous substance 
of tbe body, and by the protrusion of processes (pseudopods) 
varying in form, which either remain simple or ramify and 
anastomose. Nutrition is effected in various ways, mostly 
after the manner of the Rhizopoda. Reproduction is effected 
solely in a non-sexual manner (by monogony). Often, but 
not always, the freely moving condition alternates with a 
state of rest, during which the body surrounds itself with an 
excreted structureless covering. All Monera live in water. 
