464 Recent Literature. [May 
advances a theory of dental succession which is opposed to the 
prevalent one, and which, as it appears to us, accounts better for 
the facts. It is thus stated (p. 500): “In the Batrachia and Rep- 
tilia there are many sets of teeth developed during the life of the 
individual, of which the first arises de novo, and all the succeed- 
ing ones are derived from that which precedes it. Altogether, 
I am disposed to regard the diphyodont mammalian dentition in 
the same light: those teeth which take their origin primarily 
from the epithelial lining of the mouth are strictly homologous 
with the first set of the lower vertebrates. This would include 
in the first set the deciduous incisors, canines, molars, and the 
first true or permanent molars. The second set of the batrachian 
nines, premolars, and second true molar. The third succession 
would be represented by the last molar of the diphyodont den- 
tition.” ; 
The monograph is well illustrated by wood engravings, 
Kedzie’s Gravitation, Solar Heat, and Sun-Spots.—Profes- 
attempts to account for the source of this energy. He regards 
it as the equivalent of the heat which is radiated from the suns 
of the universe into space in such prodigious quantities, which 
_* Solar Heat, Gravitation, and S By Prof . H. Kedzie. 8vo, 1886. 
SCG Ge e. 8vo, 
