. The microscope and its revelations. ; \ \4o. .A1 PJ<Ii J*K liHI -»• / FIG. 754.—Perpendicular section oftooth of Lamna, moderately en-larged, showing network of me-dullary Fie. 755.—Transverse section of por-tion of tooth ofPristis,more highlymagnified, showing orifices of me-dullary canals, with systems ofradiating and inosculating tubuli. layers. The tubuli of the non-vascular dentine, which exists byitself in the teeth of nearly all mammalia, and which in the elephantis known as ivory, all radiate from the central cavity, and passtowards the surface of the tooth in a nearly pa
. The microscope and its revelations. ; \ \4o. .A1 PJ<Ii J*K liHI -»• / FIG. 754.—Perpendicular section oftooth of Lamna, moderately en-larged, showing network of me-dullary Fie. 755.—Transverse section of por-tion of tooth ofPristis,more highlymagnified, showing orifices of me-dullary canals, with systems ofradiating and inosculating tubuli. layers. The tubuli of the non-vascular dentine, which exists byitself in the teeth of nearly all mammalia, and which in the elephantis known as ivory, all radiate from the central cavity, and passtowards the surface of the tooth in a nearly parallel course. Theirdiameter at their largest part averages 1(nVorith of an inch; theirsmallest branches are immeasurably fine. The tubuli in their coursepresent greater and lesser undulations; the former are lew in number,but the latter are numerous; and as they occur at the same part of1 he course of several cont iguous 1 ubes t hey give rise to the appearanceof lines concentric with the centre of radiation. These •,secondarycurvatures probably indicate in dentine, as in the crabs shell, suc-cessive stages of Calcification. The tubuli are occupied, during thelife of the to
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
