DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES. 455 
next stage that the milk enamel-organ just described under- 
goes a rapid but most imperfect differentiation, and that in 
later stages (from Stage rv onwards) it has entirely disap- 
peared. At no time is there any formation of hard dental 
tissues in connection with it. Comparison of the present 
stage (11) with the next (111) proves that the labially placed 
papillary indentation now described has nothing to do with the 
formation of the papilla of the permanent third incisor. 
Behind the site of 22 the dental lamina is again much 
reduced in size for a few sections, but presently it enlarges 
slightly in the succeeding ones and again decreases. This 
almost certainly indicates the site of the future 74+. Behind 
this the lamina again enlarges, its cross-section becoming 
swollen and rounded, and after continuing thus through a 
number of sections it changes its shape, but without decreas- 
ing in sectional area, so as to form a figure elongated in cross- 
section. This gradually undergoes still further enlargement 
and elongation by a markedly deeper ingrowth of the lamina: 
this enlargement we have definitely ascertained to be the 
canine rudiment. Whether the shallower thickening of the 
lamina continuous with it in front has any significance as the 
Anlage of 72 we cannot be certain, though probably it may be 
thus interpreted. 
The shape of the canine rudiment is quite distinctive in 
early stages, for already the part of the dental lamina answer- 
ing to it manifests that tendency to disproportionately deep 
ingrowth into the surrounding connective tissue which is indi- 
cative of the future deep-seated position of the differentiated 
tooth. Its development may be followed with ease through 
all the stages from this onwards. 
But, as now differentiated, the markedly enlarged canine 
moiety of the dental lamina is not to be regarded as merely 
the rudiment of the permanent canine. Subsequent stages, 
especially that immediately succeeding, prove that from the 
present Anlage a rudimentary deciduous (milk) tooth (d*) is 
also formed. Indeed, the formation of a d* is already fore- 
shadowed by the existence of a labially directed outgrowth 
