AFFINITES AND ANALOGIES OF ORGANIZED BEINGS. 223 



form a similar function, we find that they are provided with 

 more or less similar instruments for that purpose. The re- 

 semblance, in such a case, goes no further than the fulfilment 

 of the required object, and may, therefore, be regarded as 

 unintentional, or, in common parlance, accidental. For in- 

 stance, there can be no question, that a lengthened form, 

 destitute of sharp angles, and anteriorly pointed, is the best 

 adapted for passing through the water ; and accordingly, we 

 find it to prevail, not only in fish, but in Cetacea, aquatic 

 birds, Dyticidm, Notonectidcd, cuttlefish, &c., and man imi- 

 tates it in his naval constructions. Yet we have no evidence 

 that such resemblance is intentional, or in other words, that 

 whales and Dyticidod were created for the sake of resem- 

 bling fish, but we merely suppose that in each case, the boat- 

 shaped structure was given to adapt the animal to an aquatic 

 life. The examples of these analogies are innumerable, and 

 appear to me to be owing to the fact, that the real variations 

 of circumstances which this planet affords are very few, com- 

 pared with the number of organized beings destined to inhabit 

 it, so that the performance of the same function continually 

 recurs in difierent groups of the natural system, and requires, 

 in each case, a corresponding or analogous organization. 

 Thus, e. g. there are not more than four principal varieties 

 oi locality, viz. the air, the ground, shallow water, and deep 

 w^ater. These four variations of habitat have determined the 

 structure of the four orders of birds, Insessores, Rasores, 

 Grallatores, and Natatores. Again, the twofold division of 

 food into animal and vegetable, has caused the group Bup- 

 tores to be divided off from the Insessores, and we thus get 

 the five groups under which the class, birds, is commonly 

 arranged. Now, as every other species of animal must in- 

 habit one of the above four localities, and must feed on one 

 of the above two kinds of food, it follows that the organs of 

 locomotion and of nutrition, are susceptible of comparatively 

 very few grand differences of structure, and that the inhabit- 

 ants of the same element, or the eaters of the same food, 

 must present numerous points of resemblance, quite indepen- 

 dent of their natural or essential affinities. This it is which 

 has given to distantly allied groups an appearance of regu- 

 larity in their analogies, whence has arisen the " theory of 

 representation," respecting which I will take occasion to say 

 a few words. 



The theory of representation announces, that " the con- 

 tents of every circular group are symbolically or analogi- 

 cally represented by the contents of every other circle in the 



Vol. IV.— No. 41. N. s. 2d 



