A comparative study of the chromosomes of rodents




Cross, James Cecil, 1895-

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The principal object of this study has been the comparison of the chromosome numbers and morphology of members of a relatively restricted group of mammals, the order Rodentia. While this comparison was being made an attempt was also made to establish the range of chromosome numbers for the group as well as to find out, if possible, the morphological changes of the chromosomes that have occurred during speciation. A discussion of the probable causes of the variation in numbers and morphology has been given, but it is not claimed that the exact nature of these causes has been fully determined. The matter of a base number for the group has been given consideration, and there is added evidence that forty-eight, the probable number assigned by other investigators, is the base number of chromosomes for mammals