DEVELOPMENT AND SUCCESSION OF TEETH IN PERAMELES, 529 
second dentition of higher mammals? And it is noteworthy 
that Leche’s conclusions are to a very large extent negative as 
regards the value of just those developmental features upon 
which alone Kiikenthal and Rose relied to establish the “milk” 
homology of the non-changing antemolars of Marsupials. 
It had simply been assumed by Kiikenthal and Rése that 
the presence of a residual lamina (‘‘ Ersatzleiste” of Rise), 
more or less swollen, by the lingual side of an enamel-organ 
gave sufficient assurance of the ‘ lacteal” character of the 
latter. Leche’s weighty and, as we believe, entirely valid con- 
tentions have, at any rate, opened the door to scepticism with 
regard to this doctrine. It remains to be seen upon what 
grounds Leche after all gives in his adhesion to a view which 
has been rendered assailable with the weapons he has himself 
provided. 
The Nature and Morpologieal Value of a 
“Residual Lamina.” 
In one of the numerous passages in which he discusses the 
morphological value attachable to the liberated residual dental 
lamina, Leche utters his opinion as follows :—‘* Das durch die 
Emancipation des Schmelzkeimes freigewordene Schmelz- 
leistenende bildet an und fir sich nur die Voraussetzung fiir die 
Entstehung einer Zahnanlage : je bedeutender dieser Schmelz- 
leistentheil ist, desto grésser ist die Pradisposition fiir die 
Bildung eines neuen Zahnes. Und wir k6onnen hinzufigen: 
ist dieses Schmelzleistenende wirklich kolbenoder knospen- 
formig angeschwollen und von einem Zahnsackchen umgeben 
erst dann ist diese Moglichkeit als realisirt zu betrachten, erst 
dann konnen wir von einer (knospenformigen) Schmelzkei- 
manlage reden, einerlei ob diese Anlage sich spater weiter 
entwickelt oder nicht ” (8, p. 134). 
It will be remarked that this passage is by itself quite inde- 
cisive. It merely expresses the author’s view that any free 
end of the dental lamina swollen (i.e. “kolbig” on section), 
and surrounded by an investment of condensed connective 
tissue, has a right to be regarded as an enamel-germ, though 
