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nervous system is formed of a chain of separate rounded masses, 
connected together by thin cords, and the whole nervous system 
lies in the part of the body nearest the ground. ‘These are 
classed as Invertebrates. Now the Vertebrates, having more 
highly-developed organs, bringing them into more varied relations 
with the external world, having a more complete structure, more 
varied functions, are placed above the Invertebrates. Consider 
for a moment the difference between a bird singing in the 
branches of a tree and a snail crawling in the grass beneath. 
How vast the interval between them! What an illustration, we 
say, of the great scheme of the world’s development, and of the 
steps in its progressive life, for the Vertebrate is higher than 
the mollusc and comes later on the scene. This is too partial 
a view. Reckoned among the Vertebrates is a pale, ghost-like 
creature, with a mere apology for a backbone, without a brain, 
with scarcely any organs of sense, whose dull monotony of 
existence is only broken by faint variations of light and shade 
as it roams among the mud and weeds of the shallow estuary 
in which its existence is passed. Compare this with the bee, 
winging its way in the sunshine, sensitive to the odour and colour 
of flowers, with faculties seemingly more than human in their co- 
ordination to the unconscious ends and aims of existence. 
Teaching also in the subordination of individual liberty to the 
welfare of the community, “The act of order to a settled 
kingdom.” Which shall we reckon the highest in the scale of 
life, the lancelet or the bee? The celebrated Von Baer thought 
the bee more highly organized not only than this specimen of one 
of the lowest orders of fish, but than any member of the whole 
class of fishes. 
Yet the Vertebrate, we have said, is higher than the 
Invertebrate! Does structure then measure life? This is not a 
solitary instance ; it is but a type of the difficulty which meets 
the systematist on every side. Supposing we take only a branch 
of our Tree of Life, and endeavour to place the groups which 
compose it, or the individual of the groups, in serial rank, how is 
he to proceed? “By noting,” we are told, “the points of 
structure which are fundamental and essential.” Yes, but what 
to one classifier is fundamental and essential, to another is not. 
Different observers place different values on the same structure, 
In that endless mutation of form which the kingdom of the In- 
vertebrates presents to us, there is a vast number of groups whose 
relationship to one another cannot even be represented in space 
of two dimensions. Only with length, breadth, and depth can we 
picture to ourselves these cycles within cycles in endless com 
plexity. If, then, this obtains in the Invertebrate kingdom, is it 
not a presumption that the orders, families, species, etc., of the 
Vertebrates should be regarded in the same manner P We must 
give up our “ Tree of Life.”’ The picture is illusory. It implies 
