224 RAINEY, ON DENTAL TISSUES. 
been taken up by their aggregated molecules are a proof of 
the other. Hence, the probable questions which will arise 
are,—whether these effects are entirely due, to the direct 
and sole influence of vitality, or to the exclusive operation of 
physical forces? In my opinion neither of these views is 
correct, and one is just as untenable as the other. I am not 
aware that the latter has any advocates, but I believe that 
the former is the view generally entertained by physiologists, 
and that the strictly physiological part of the cytoblast 'theory 
is based upon it. To me the truth seems to be between the two 
extremes, the above-mentioned chemical and mechanical effects 
being, in my opinion, produced directly by physical and mecha- 
nical agency, but under the control of a general vital principle. 
According to this view, the function performed by the nu- 
cleated corpuscles of enamel-, dentine-, and bone-pulp, is 
chemical, each individual corpuscle being designed to ela- 
borate a material whose elements are brought to it by the 
blood-vessels. Now, it is no more improbable that there 
should be in the bodies of animals a strictly chemical appa- 
ratus than an electric one, as in the Torpedo, or an optical 
one, as exemplified by the dioptrical parts of the eye. 
Indeed, not only animal, but vegetable structures perform 
an endless variety of chemical operations, and ought, there- 
fore, likewise to abound in chemical apparatus. And it is 
in no way inconsistent with analogy to suppose that the 
nucleated particle found in the earlier states of vegetable 
cells is strictly an organ of this kind, and analogous to a 
nucleated corpuscle of the enamel-organ, and not a mere tran- 
sitional form of vegetable tissue, as some suppose. ‘This sub- 
ject I hope to consider more fully in another communication 
in a subsequent number of the journal, showing the applica- 
tion of the principle of molecular coalescence to the formation 
and structure of starch-granules. It may be further observed 
concerning the influence of vitality, that if the form of a 
perfectly developed tooth be considered in reference to its 
adaptation to the place and circumstances under which 
it is designed and required to act, it will be at once obvious 
that not only a vital, but an intelligent principle has been 
concerned in originating and directing the chemical and 
mechanical forces to which it owes its construction. And 
further, as the size and shape of an entire tooth depends 
upon the number, form, and arrangement of the several 
parts composing it, it is a fair inference that the same design 
and intelligence which originate and direct the construction 
of the whole, also originate and direct the physical pro- 
cesses concerned in the formation of the parts ; and that, 
