THE ZooLogist—OcToBER, 1876. 5095 
-when it moves it pushes out any part of its body which is con- 
venient. When it wishes to assimilate food, it can hardly be said 
to eat, it places itself over or against the food, which then passes 
directly into it through apy part. 
For such animals to be able to maintain their existence, the 
surrounding conditions of life—that is, a supply of food and the 
absence of a liability to mechanical or chemical injury—must be — 
of the most favourable kind. Consequently we find that one of 
the first things done by animals of this type is to cover their 
delicate bodies with a tiny calcareous shell. 
We have here, in one of the simplest forms of physical life, 
voluntary action, with power of changing the form of its body, 
power of adding to that body from other substances so as to grow 
by taking food, and a power of separating from itself a part which 
shall commence a new life with similar powers. 
Such animals form the models of the ultimate parts from which 
alt the tissues of all animals are developed. 
Physiological laws, then, instead of having chemical or me- 
chanical laws as their highest principles, can be best explained as 
habits of action. Hach tissue and organ of the body is the record 
of voluntary action passed into habit and perpetuated into instinct 
by the “survival of the fittest,” or some other law of suitability to 
the surrounding conditions of life. Every animal has therefore 
within it all the instincts of which its organs or tissues are 
evidence. 
Here the question of individuality thrusts itself upon us. Is it 
the same life that continues on from parent to offspring? How do 
all these aggregations of separate animals lose their individuality 
and humbly class themselves as cells with fixed duties? 
Does intelligence pass down from father to son? Have we dim 
memories of what our parents did? or does each individual begin 
his own experience and develope his own intelligence with such aid 
as the arrangement of his inherited organization may give him? 
In many of the lower forms, the individuality of community only 
seems to have been arrived at. A sponge, for instance, is built up 
of a great number of small particles into canals and chambers, 
each of which particles “is provided with a cilium,” to quote 
Prof. Huxley again, “and as all these cilia work in one direction 
they sweep water out in that direction. The currents of water 
sweep along such matters as are suspended in them, and these are 
