392 H. E. JORDAN 



of the canine tooth of a newborn kitten certain spheroidal glob- 

 ules of various sizes scattered throughout the enamel pulp. 

 These I tentatively interpreted as superfluous enamel globules 

 formed by the cells of the stellate reticulum and the stratum 

 intermedium. That they are of the nature of foreign bodies, 

 however, seemed proved by the fact that some were ingested by 

 giant-cells formed in the enamel pulp largely from the cells of 

 the stratum intermedium. Possibly these globules are homol- 

 ogous with the albuminoid globules described by Williams in 

 the stratum intermedium. Whatever value this substance may 

 actually have in relation to enamel formation, its presence in 

 the stellate reticulum suggests that this tissue has amelogenic 

 capacity. However this may be, it seems clear on logical grounds 

 that since the capillaries are excluded from direct contact with 

 the ameloblasts, being separated therefrom by the varying width 

 of the enamel organ at any point, the nutritive materials for 

 the support of amelogenesis must be either transported from the 

 extrapulpar blood vessels to the ameloblasts by the cells of the 

 stellate reticulum, or a complete supply must have been originally 

 stored in the stellate reticulum. The most plausible interpreta- 

 tion of available histologic evidence would seem to be that an 

 original supply of amelogenic materials stored in the stellate 

 reticulum is replenished peripherally from the extensive blood 

 supply covering the outer tunic of the enamel organ. That this 

 is probably the case is suggested also by the fact that in most 

 mammalian teeth, at the stage of development at any point when 

 the blood vessels come to lie nearest the ameloblasts, due to the 

 disappearance of the stellate reticulum in the formation of the 

 membrane of Nasmyth, enamel formation is complete. This 

 interpretation is further supported by the fact that when a stellate 

 reticulum is lacking, as on the rat's incisors, the blood vessels are 

 brought relatively much closer to the ameloblasts. 



e. The relation of the amelohlasts to dentinogenesis 



This investigation is not concerned with the question of the 

 origin of that membrane ('membranapreformativa') upon one side 

 of which the ameloblasts deposit uncalcified enamel and upon the 



