Chap. I. DEGREES AND KINDS OF RELATIONSHIP. 21 



wluMi tlioy have maintiuncd, for instance, that every l)one existing in any Vertebrate 

 must have its counterpart in every other species of that type. To assume such a 

 iniifonnity among animals, would amount to denying to the Creator even as mucli 

 freedom in expressing his thoughts as man enjoys. 



If it l)e true, as pointed out above, that all animals are constnicted upon four 

 dift'erent plans of structure, in such a manner that all the different kinds of animals 

 are only difterent expressions of these fundamental formulae, ^^^c may ■well compare 

 the whole animal kingdom to a work illustrating four great ideas, between which 

 there is no other connecting link than the unity exhibited in the eggs in which their 

 most diversified manifestations are first embodied in an embryonic form, to undergo 

 a series of transformation.s, and appear in the end in that wonderful variety of inde- 

 pendent living beings which inhabit our globe, or have inhabited it from the earliest 

 period of the existence of life upon its surflice. 



The most surprising feature of the anhnal kingdom seems, however, to me to 

 rest neither in its diversity, nor in the various degrees of complication of its struc- 

 ture, nor in the close affinity of some of its representatives, while others are so 

 different, nor in the manifold I'elations of all of them to one another and the sur- 

 rounding world, but in the circum.stance that beings endow^ed ^vith such different and 

 such unequal gifts should nevertheless constitute an harmonious whole, intelligibly 

 connected in all its parts. 



SECTION YI. 



VARIOUS DEGREE.S AND DIFFERENT KINDS OF RELATIONSHIP AMONG ANIMALS. 



The degrees of relationship existing between different animals are most diversified. 

 They are not only akin as representatives of the same species, bearing as such the 

 closest resemblance to one another; different species may also be related as members 

 of the same genus, the rci)resentatives of different genera may belong to the same 

 family, and the same order may contain different families, the same class different 

 ordei-s, and the same type several classes. The existence of different degrees of 

 affinity between animals and plants which have not the remotest genealogical connec- 

 tion, which live in the most distant parts of the world, wliicli liave existed in periods 

 long gone by in the history of our earth, is a fact beyond dispute, at least, within 

 certain limits, no longer controverted by Avell informed observei-s. Upon what can 

 this be founded ? Is it that the retentive capacity of the memory of the physical 

 forces at work ujion this globe is such, that after bringing forth a type according to 

 one pattern, in the infancy of this earth, that pattern was adhered to under conditions. 



