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THREE PLATES (FIFTEEN FIGURES)Since the time of Boll in 1868 the problem of the innervation of the teeth has been a moot one. The controversy centers about whether nerve fibers from the dental pulp enter the dentin o r are confined solely to the pulp. Other differences concern the course, relationship to the adontoblasts, and mode of termination of the nerve fibers.Technique seems largely responsible for the discrepancies in the results of the different investigators. Various methods for the impregnation of nerves which give excellent results with other tissues are found to be capricious when applied to teeth. It is not unlikely that decalcification often renders the nerves in teeth less acceptable to impregnation with reduced silver and gold. Also, many investigators have confined their studies entirely to human teeth, which not always being in the best of condition are further complicated in having many nerves.Because the extensive literature on this subject has been reviewed adequately, an historical survey is unnecessary. More recent reviews include those of Windle ( '34), van der Sprenkel ( '35) and Brashear ( '37).Entering into a study of the innervation of teeth without prescience, the purpose is to see whether with a large number of teeth from easily obtainable animals of known ages, some

TWO PLATES (SEVEN FIGURES)Tlie body of a 31-year-old female Iiidiaii elephant u7as brought into the anatomical laboratory a few hours after death. Among the several tissues and organs removed from the body were the teeth. From the bases of the tusks thc pul1)s protruded, so that with a little care and gentle traction, each pulp was extracted in one piece without tearing.Because the tusks grow continuously I was interested to know if the innervation of the pulps was similar to that observed in the incisor teeth of rodents. Also, because of the greater size of the pulp of the elephant's tusk, I wanted to see if the nerve fibers were proportionately larger aiid more numerous.The extracted pulps were put into an aqueous solution of formaldehyde (9 : 1) and after fixation they were clcliydratecl slowly by gradually increasing the strengths of alcohol. While in 93"/0 alcohol each pulp mas cut transversely into four pieces of about equal lengths, and the two more basal pieces were cut again longitudinally. Embedding was in paraffin. Groups of serial sections were cut 5 a i d 25 p thick. Tlie thinner sections were stained by the Heidenhain 'azaii' method and bjthe Masson 'trichrome' method for a study of cellular details, while the thicker sections were impregnated according to the Bodian activated protargol technique for nerve fibers and cndings.