102 Mr. J. D. Dana on Zoophytes. 



partly isolated and terminating abruptly, others graduating into 

 the different series by frequent blendings or anastomosings, and 

 often between different lines detecting a serial parallelism : in this 

 way the network is finally completed to the mind's eye. 



When the relations are fully understood, we are ready to divide 

 off into classes, orders, and the smaller subdivisions, cutting the 

 threads here and there, as shall best exhibit the general character 

 of the whole, remembering to make the corresponding divisions of 

 equivalent importance and character. The institution of these va- 

 rious groups is not properly classifying ; for the classification is 

 completed when the branchings and interlinkings of affinities are 

 made out. Subdivisions with appropriate names are however ne- 

 cessary, to aid the memory and convey this knowledge in words. 

 Genera are convenient artificial sections, based on natural affini- 

 ties ; and very commonly they shade almost imperceptibly into 

 one another. Whoever has attempted to lay out classes and their 

 families and genera, has perceived the interlinkings, and felt the 

 perplexity they produced. It may often have seemed vexatious to 

 the systematist to have had a well-characterized family or genus 

 spoiled in its characteristic, and exceptions introduced, by the dis- 

 covery of new species which blend it with another group, before 

 considered quite distinct. But such perplexities will not be per- 

 ceived, if we follow nature with docility, and make it our aim 

 to bring out prominently the various shadings between subdivi- 

 sions. The true object of classification is not to dissect the 

 departments of life into as many distinct parts as possible for 

 display like anatomical preparations ; but to illustrate the system 

 of nature in its unity, and exhibit the myriad parts blended in 

 one concordant whole. 



The modifications of structure in living beings evidently pro- 

 ceed, to a great extent, from the nature of the world we inhabit, 

 and the general laws and necessities of life. There are air, earth, 

 and water, and these have their varieties of condition. Plants 

 and animals offer other sites for living beings. The same cir- 

 cumstances may be said to call for the variety of size which 

 exists in nature, for otherwise there would be possible conditions 

 for existence unoccupied. The general nature of life and its 

 modes of exhibition, with the primary systems of structure, being 

 determined upon in infinite wisdom, we need attribute no other 

 plan to creative power than that of the simple adaptation of life, 

 as thus constituted, to the conditions the world affords. Circles 

 and numerical relations may amuse the imagination ; but we 

 have no evidence that the Hand which made was confined by 

 such prescribed courses. We cannot fail to see, however, that in 

 the primary plan of structure in living beings, certain organs or 

 their parts, through extended groups, have been limited by fixed 



