570 MERISTIC VARIATION. [PART I. 



<>f indi-pi-nd'-nt division and of separate Variation. Single digits for 

 instance may thus be independently hypertrophied as a whole, single 

 segments or single appendages or pairs of appendages may be differ- 

 entiated in some special way, and ^> forth. 



At this point reference may again be made to that extraordinary 

 Discontinuity of Variation appearing in what I have called Ho- 

 mceosis, so strikingly seen in the few Arthropod cases given (p. 14<i i, 

 and so common in flowering plants. In these changes a limb, 

 a floral segment, or some other member, though itself a group of 

 miscellaneous tissues, may suddenly appear in the likeness of some 

 other member of the series, assuming at one step the condition to 

 which the member copied attained presumably by a long course of 

 Evolution. 



Many times in the course of this work we have had occasion to 

 r the modifications in the conception of Homology demanded 

 by the facts of Variation. It is needless to speak further of this 

 matter here, and the reader is referred to pp. 12o, 191, 2G!>, M'.i4 

 and 417, where the .subject is discussed in relation to Linear Sen.-- 

 of several kinds, and to the facts given in Chapter XVI and at 

 p. 433 bearing on the same questions in their application to Radial 

 Series. The outcome of these considerations shews, as I think, 

 that the attribution of strict individuality to each member of a 

 series of repeated parts leads to absurdity, and that in Variation 

 such individuality may be set aside even in a series of differentiated 

 members. It appears that the number of the series may be in- 

 creased in several ways not absolutely distinct, that a single 

 member of the series may be represented by two members, that 

 a terminal member may be added to the series, and also that the 

 number of the members may change, no member precisely corre- 

 sponding in the new total to any one member of the old series : in 

 short, that with numerical change resulting from Meristic Variation 

 there may be a redistribution of differentiation. 



But though this is, in my judgment, a fact of great consequence, 

 its relation to the Study of Variation is merely incidental. It is 

 not so much that to enlarge the conception of Homology so as to 

 include the phenomena of Meristic Variation is a direct help, as 

 that to maintain the old view is a hindrance and keeps up an 

 obstacle in the way of any attempt to apprehend the real nature 

 of the phenomena of Division, and hence of Meristic Variation. 

 So long as it is supposed that each member of a series of repeated 

 parts is literally individual, it is impossible to form any conception 

 of Division that shall include the facts of Meristic Variation, for in 

 Variation it is found that the members are divisible. 



It is an unfortunate thing that the study of Homology lias been 

 raised from its proper place. The study of Homologies was at first 

 undertaken as a means of analyzing the structural evidences of 

 relationship, and hence of Evolution. This is its proper work and 



