Abstract
Summary
1. The number of fungiform and foliate papillae were counted on the tongues of 100 recently trapped wild Norway rats and of 20 wild Alexandrine rats, and compared with the number on the tongues of 103 domestic Norway rats. 2. The number of fungiform papillae on the tongues of the domestic Norway rats ranged from 114 to 221, with a mean of 178.3, while for the recently trapped wild Norway ancestors it ranged from 167 to 271, with a mean of 217.9, and for the Alexandrine rats it ranged from 147 to 231, with a mean of 191.5. The mean of the domestic Norway rat thus showed a 17% reduction from that of its wild ancestor. 3. The number of foliate papillae ranged from 8 to 16 for the domestic rats, with a mean of 11.98, and ranged from 7 to 20 for the wild Norways, with a mean of 11.46. The 2 strains thus showed essentially the same number of foliate papillae, but both showed fewer than are found in Alexandrine rats, in which the number of papillae ranged from 9 to 18, and had a mean of 13.5. 4. In general, both types of papillae were more uniform in size, structure and distribution in the wild than in the domestic strains.
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