94 
may be doubted if this conclusion is. allowable; at any rate the 
teeth of the whale-bone whales. are so extremely rudimentary and 
with so many individual variations that no sure conclusions can 
rest upon them. The same is the case with the far less reduced 
dentitions of Odontoceti, Edentata and even of Myrmecobius, Otocyon, 
Proteles, Pinnipedia etc. 
Can the normal dentitions support. the Concrescence Theory 
better? Råse and others have shown that the more complicated 
teeth also germinate with one isolated tooth-papilla - correspon- 
ding to each future main cusp, only after a while the papillæ 
coalesce, and from this ontogenetic development he concludes to the 
"phylogenetic evolution. Certainly the "biogenetisches Grundgesetz” 
has. been a good deal idolized, especially in Haeckel's country; m 
its broad features it can no doubt be said to hold good, but entering 
into details one finds so many exceptions that one can hardly speak 
of a rule, still. less of a fundamental law; one has always to be 
cautious in speaking of the ontogeny recapitulating the phylogeny- 
But if this "law" were really applicable to the mammalian teeth, 
were Råse's conclusions legitimate? The starting-point of the tooth- 
formation is certainly the enamel-organ, formed by an outgrowth 
from the dental lamina — the tooth having thus preserved its 
primeval nature as a tegumentary structure. No doubt there 
is always one and but one enamel-organ for every tooth (even in 
Manis Råse himself has found it). It.is only when this organ has 
reached a certain point of development that mesodermal tooth-pa- 
pillæ are formed in connection with it, one papilla for every future 
main cusp. Therefore the enamel organ must be considered as the 
primary. factor and the tooth-papillæ as the secondary factor in 
tooth-development; the primary element being single, not too much 
stress can be laid on the secondary being divided. To my mind 
the embryological development is only suggestive of every tooth 
being a single organ. — When Råse and others endeavour to ho- 
mologise the anterior outer cusp of upper molars (paracone) with 
the lower protoconid on. account of its early appearance, this con- 
