212 
On the Structure and Movs of Formation of the Drentar 
Tissues, according to the PrincipLe of ‘ MoLecuLaR 
CoaLescENce.” By Grorce Rainey, M.R.C.S., and Lec- 
turer and Demonstrator of Surgical and Microscopical 
Anatomy at St. Thomas’s Hospital. 
In a paper contained in the ‘ British and Foreign Medico- 
Chirurgical Review,’ for October, 1857, “On the Elementary 
Formation of the Skeleton,’ I have intimated that the 
globular form of dentine noticed by some of the later 
writers on the dental-tissues, is the result of the same 
process of molecular coalescence as that by which bone 
and shell are formed; and that the so-called ‘ dentinal 
tubules” are merely spaces bounded directly by the den- 
tine-fibres, and the partially coalesced dentine - globules. 
As, at that time, I was not aware that a similar view of the 
nature of these passages had been published by M. Rasch- 
kow, any observations of mine, however demonstrative of 
the fact, can only be regarded as confirmatory of his. This 
view of the nature of these passages had, to my knowledge, 
no supporters among those who had written upon the subject 
in this country, being supposed to have its origin entirely in 
the fibrous appearance presented by dentine under a low 
magnifying power, and thus Raschkow’s view was passed over 
as incorrect. I may remark, that as there are few structures 
which have been so minutely and carefully examined as the 
dental tissues, it must follow, that so far as microscopical 
appearances are concerned, it will be impossible to add much 
to what has, with more or less minuteness and accuracy, 
been described, and therefore I shall have but little to com- 
municate strictly of an anatomical character which will be 
new. But originality in this respect is not, im this commu- 
nication, my object, which is to give the proper interpretation 
of appearances already described, and to show that they 
admit of being accounted for, and their mode of formation 
demonstrated on the same principle of molecular coalescence 
as has been applied to the formation of shell-tissues. I 
may further notice, that as this article must be as brief as 
possible, only such details of the structure of the dental 
tissues, and the organs concerned in forming them, will be in- 
troduced, as are absolutely necessary to render the physiolo- 
gical observations and explanations intelligible. 
In discussing the subject, two descriptions of parts will 
require to be considered; namely, the tooth itself, and the 
