80 MEANING OF ORDERS. 
the idea that the system of man, the most perfect 
created being, is the measure for the whole Ani- 
mal Kingdom, and that in analyzing his organi- 
zation we have the clew to all organized beings. 
The structure of man includes two systems of 
organs: those which maintain the body in its in- 
tegrity, and which he shares in some sort with 
the lower animals, — the organs of digestion, cir- 
culation, respiration, and reproduction ; and that 
higher system of organs, the brain, spinal mar- 
row, and nerves, with the organs of sense, on 
which all the manifestations of the intelligent 
faculties depend, and by which his relations to 
the external world are established and controlled : 
the whole being supported by a solid bony frame 
and surrounded by flesh, muscles,.and skin. On 
account of this fleshy envelope of the hard parts 
in all the higher animals, Oken divided the Ani- 
mal Kingdom into two groups, the Vertebrates 
and Invertebrates, or, as he called them, the 
“ Hingeweide und Fleisch- Thiere,’ — which we 
may translate as the Intestinal Animals, or those 
that represent the intestinal systems of organs, 
and the Flesh Animals, or those that combine all 
the systems of organs under one envelope of 
flesh. Let us examine a little more closely this 
singular theory, by which each branch of the In- 
vertebrates becomes, as it were, the exponent of 
a special system of organs, while the Vertebrates, 
