83 
Observation carried on impartially and without prejudgment, 
by comparison and inquiry, thus makes it indubitable that the 
so-called ‘‘instinct” of animals is nothing else than the sum total 
of the soul-activities which were originally acquired through adapt- 
ation, and have become fixed by habit and passed on by inheritance 
from generation to generation. Executed originally w7t# conscious- 
ness and consideration, many of the instinctive actions of animals 
have become wzconscious in the course of time, just as in the same 
way happens also in the habitual intellectual actions of man. 
Consequently, neither is instinct an exclusive brain-property of the 
animal, nor intelligence a special prerogative of man. On the 
contrary, there is perceived by the impartial study of comparative 
psychology, a long, long ladder of steps of gradual progress and 
development of forms of soul-life, leading down step by step from 
the higher to the lower men, from the highly complicated to the 
simple animals, even down to yonder simple worm, whose simple 
nerve-knots furnish the starting point for all the countless brain 
forms of this ladder. 
As in reality no break exists anywhere in this ladder, and as 
the simple soul-apparatus of our worm already contains all the 
elementary forms—nerves, sense organs, and muscles—of which in 
the most highly complicated manner the wonderful soul-apparatus 
of man is constructed ; so it is now universally agreed by all in- 
quirers in natural science, that in all these animals which are 
furnished with a merve-system, there exists a soul-life, in fact, a 
psyche. 
III. 
But now how stands the case with those lower animals which 
are without a nerve-system, even of the simplest kind, e.g., corals, 
polyps, sponges, &c.? Have we in the want of a nerve-system 
what constitutes the lower limit of soul-life? Or is there here a 
soul without nerves? Scientific men of note, e.g., Virchow and 
Du Bois-Reymond reply in the negative to our last question, and 
maintain that there can be no idea of the existence of real soul-life 
