302 THE HISTORY OF CREATION. 
(for example, an Ameeba, or a single-celled plant), could 
never perform. 
No sensible person supposes that carefully devised insti- 
tutions, which have been established for the good of the 
whole, as well as for the individual, in every human state, 
are the results of the action of a personal and supernatural 
Creator, acting for a definite purpose. On the contrary, 
every one knows that these useful institutions of organiza- 
tion in the state are the consequences of the co-operation of 
the individual citizens and their common government, as 
well as of adaptation to the conditions of existence of the 
outer world. Just in the same way we must judge of the 
many-celled organism. In it also all the useful arrangements 
are solely the natural and necessary result of the co-operation, 
differentiation, and perfecting of the individual citizens— 
the cells—and by no means the artificial arrangements of a 
Creator acting for a definite purpose. If we rightly consider 
this comparison, and pursue it further, we can distinctly 
see the perversity of that dualistic conception of nature 
which discovers the action of a creative plan of construction 
in the various adaptations of the organization of living 
things. 
Let us pursue the individual development of the verte- 
brate animal body a few stages further, and see what is next 
done by the citizens of this embryonic organism. In the 
central line of the violin-shaped dise, which is composed of 
the three cellular germ-layers, there arises a straight deli- 
cate furrow, the so-called “ primitive streak,” by which the 
violin-shaped body is divided into two equal lateral halves— 
aright and a left part or “antimer.” On both sides of that 
streak: or furrow, the upper or external germ-layer rises in 
