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IOWA ACADEMY OF SCIENCE 
Med. S. — Medullary sheath. 
Axis-C. — Axis-cylind'er. 
N eii. — N eurilemma. 
Hen. — Henle’s sheath. 
Hen.-N. — Nuclei of Henle’s sheath . 
End. f. — End fibrils. 
End. b. — End bulbs. 
Flex. — Plexus. 
The size of the fibres are exaggerated. 
