BY MOLECULAR COALESCENCE. 3 
formed is in a solution of a viscid material, its form, in 
the place of being crystallme as when produced in the 
same manner in pure or common water, is globular, and 
that in this state it possesses, in a remarkable manner, 
the property of coalescing with contiguous particles of the 
same compound, as well as of mtimately blending with 
such substances as, in its molecular state, it may happen 
to be brought mto contact with; so that the minute sphe- 
rules in which it first appears, if allowed to remain suffi- 
ciently long within the sphere of their mutual attractions, 
coalesce into large, spherical, transparent calculi, which, 
if suffered to remain a sufficient time on the surface of a 
glass slide, will leave permanently impressed upon it the 
form of the part of the calculus which was in contact with 
the glass. On reflecting upon these properties of this 
form of carbonate of lime, and contrasting the conditions 
under which it is formed im the experimental process, with 
those which I considered would most probably be found 
to be present in animal calcifying tissues—the carbonate 
being in these formed and deposited in contact with a 
certain amount of viscid animal matter—I expected to 
find the same form of carbonate existing in the earliest 
states of calcification of animal tissues, and possessed of 
the same property of coalescmg and intimately blending 
with contiguous structures, as that produced artificially. 
Under this impression I commenced the examination of 
shell-structures; but, though expecting to find some 
analogy, | had no thought of meeting with so perfect a 
resemblance between them, which in some instances was 
so complete, that, in small portions of the two products 
I was unable to distinguish one from the other, even by 
the aid of polarized light. To obtain the most satisfactory 
results in the investigation of the process of calcification 
