56 THE HISTORY OF CREATION. 
most important of all organisms to the whole science of 
biology, and especially to general genealogy. For it is 
evident that the Amocebz originally arose out of simple 
Monera (Protamcebze), by the important process of segre- 
gation taking place in their homogeneous viscid body—the 
differentiation of an inner kernel from the surrounding 
plasma. By this means the great progress from a simple 
cytod (without kernel) into a real cell (with kernel) was 
accomplished (compare Fig. 8 A and Fig. 10 B). As some of 
these cells at an early stage encased themselves by secreting 
a hardened membrane, tucy formed the first vegetable cells, 
while others, remaining naked, developed into the first 
ageregates of animal cells. The presence or absence of an 
encircling hard membrane forms the most important, 
although by no means the entire, difference of form between 
animal and vegetable cells. As vegetable cells even at an 
early stage enclose themselves within their hard, thick, and 
solid cellular shell, like that of the Amcebz in a state of rest 
(fig. 10 A), they remain more independent and less accessible 
to the influences of the outer world than are the soft animal 
cells, which are in most cases naked, or merely covered by a 
thin pliable membrane. But in consequence of this the 
vegetable cells cannot combine,as do the animal cells, for 
the construction of higher and composite fibrous tracts, for 
example, the nervous and muscular tissues. It is probable 
that, in the case of the most ancient single-celled organisms, 
there must have developed at an early stage the very im- 
portant difference in the animal and vegetable mode of - 
receiving food. The most ancient single-celled animals, being 
naked cells, could admit solid particles into the interior of 
‘heir soft bodies, as do the Amcepe (ig. 10 B) and the 
