MACK113 — FIRST TRACES OP THE SUCCESSION OP LIFE. 
343 
The first glance at the familiar objects around us assures us tliat 
all living things have not the same values of structure or the like 
capabilities of life. We perceive at once that some are of far lower 
grades both of intelligence and action ; that in point of fact there is 
a scale of development of tlie social rank both of animals and 
vegetables. These conditions are so apparent and so well known 
that it would be useless to dwell upon them. We proceed therefore 
at once to mark out the divisions of the animal and vegetable king- 
doms, and the particular characters by which each is indicated, 
premising that, as in the inorganic world there is no decided 
natm'al line of division between one rock-mass and the others, one 
stratum and another, in the succession of formation, and that what 
appears a break in the series in one place is filled up by some 
deposit in another, so in the organic world each genus, family, and 
order are so linked by modifications and divergences to others, that 
the actual lines of division are essentially arbitrary, and especially in 
the more minute scientific and natui'al divisions, as between species, 
genera, and families ; the liigher groups appearing, however, as far 
as om' present knowledge extends, to be merely linked together by 
similitudes, or by the devarication of one type into an apparent re- 
semblance to another rather than by any natural aflinities between 
them. 
We now present in Table I. the primary constituent members of 
these great divisions as nearly as may be in the ascending order of 
their organic development and rank, thus placing Man, the highest, 
at the top, and the Rhizopods — Protozoans at the base of the series. 
The groups of animal-forms must not be altogether regarded as in- 
dicating a progressive iiicreased ranlc of organization ; many of 
them are of equal value with each other, and the exact position of 
others has not been thoroughly determined. Moreover, no system 
of classification of organic forms, whether vegetable or animal, can 
be as yet regarded as perfect ; the best can only be considered artifi- 
cial and provisional, requiring many modifications and improve- 
ments ; hence the stiident or general reader must not therefore 
be dismayed at the difference of position assigTied by different 
naturalists to particular organisms, nor think that naturalists are 
ignorantly difiering from each other in theii' ideas. Nor must they 
