CHAPTER IV 



MERISTIC VARIATION 



Meristic variation has reference to a deviation in the number 

 or arrangement of repeated parts involved in the plan or pattern 

 upon which any particular organism is built. 



A plant or an animal is not an amorphous lump of living 

 matter. On the contrary, it is made up of parts, each of which has 

 a kind of identity of its own, many of which are similar, and all 

 of which are definitely related and placed in some sort of orderly 

 arrangement. 



Reflection discloses the fact that each organism is developed 

 upon a specific plan, essentially different from that of any other, 

 and that with most organisms the pattern is composed of a defi- 

 nite number of similar parts more or less repeated. 



Thus the chicken has two legs, and the horse has four legs, 

 that are more or less alike. The flower has many petals, the 

 corn plant many leaves ; the spinal column is composed of vertebra 

 very much alike, and organisms generally possess many parts 

 that more or less closely resemble one another. 



From this it appears that the individual animal or plant is 

 not a unit in respect to form, but rather that it is made up of 

 many units, some of which are practical duplicates. Thus the 

 idea of multiple parts in orderly arrangement (merism) comes at 

 once into the study, and variation in the number or character of 

 these repeated parts (meristic variation) is a broad and compli- 

 cated subject affording considerable insight into the nature of 

 variation. Accordingly it is profitable to pursue it at considerable 

 length, not so much for the material involved, which consists 

 largely of abnormalities of no practical interest or value, but 

 because no other phase of variation affords so much information 

 upon the real nature of living matter and its adherence to or 

 deviation from a definite plan. 



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