7O THE HISTORY OF CREATION. 
nitrogenous cell-substance, or protoplasm. In most genuine 
animals, on the other hand, the skeleton generally consists 
either of nitrogenous combinations (chitin, etc.) or of cal- 
careous earth. In this respect some Protista are more like 
plants, others more like animals. In many of them the 
skeleton is principally or entirely formed of calcareous earth, 
which is met with both in animal and vegetable bodies. 
But the active vital substance in all cases is the mucous 
protoplasm. 
In regard to the form of the Protista, it is to be remarked 
that the individuality cf their body almost always remains 
at an extremely low stage of development. Very many Pro- 
tista remain for life simple plastids or individuals of the first 
order. Others, indeed, form colonies or republics of plastids 
by the union of several individuals. But even these higher 
individuals of the second order, formed by the combination 
of simple plastids, for the most part remain at a very low 
stage of development. The members of such communities 
among the Protista remain very similar one to another, and 
never, or only ina slight degree, commence a division of 
labour, and are consequently as little able to render their 
community fit for higher functions as are, for example, the 
savages of Australia. The community of the plastids re- 
mains in most cases very loose, and each single plastid 
retains in a great measure its own individual independence. 
A second structural characteristic, which next to their low 
stage of individuality especially distinguishes the Protista, 
is the low stage of development of their stereometrical 
fundamental forms. As I have shown in my theory of 
fundamental forms (in the fourth book of the General 
Morphology), a definite geometrical fundamental form can 
