24 FORMATION OF SHELLS OF ANIMALS, ETC., 
The form of laminz just described is the effect only of 
one cause of lamination; the concentric divisions thus 
produced occur chiefly in the smaller spherules, where they 
are generally more distinct and complete than those which 
IT am about to describe. The calculi in which the nature 
of the process of lamination now to be considered can 
be best shown, are those which are formed by the coales- 
cence of several small globules of nearly the same size. 
The first stage in the formation of such calculi is a 
spherical conglomeration of these globules producing a 
mulberry-like appearance, (See fig. 4, 6, c, d,) and a 
form closely resembling that of the corpuscle called by 
pathologists a glomerulus, although that is composed of 
particles of oil. The next is the disintegration of these 
spherical particles which takes place first in the peripheral 
ones. In this process every vestige of their original 
form and structure is destroyed, and they become re- 
duced to an amorphous granular mass. Next, the mole- 
cules nearest to the surface coalescing, form a clear ring 
completely surrounding the amorphous matter occupying 
its interior. (See fig. 4, 4.) The further progress of the 
processes of disintegration and subsequent coalescence is 
marked by the increase in width of the circumferential 
bright ring, just as the central amorphous part diminishes, 
showing that the one is formed at the expense of the 
other, (See fig. 4, d,) until all the latter has disappeared, 
and is replaced by a succession of bright concentric 
laminz. These calculi, when dried and examined by re- 
flected light, have very much the appearance of small 
pearls, especially the brightest of them; but after being 
immersed in Canada balsam, and examined in the same 
manner, they appear to consist of a glassy case, filled 
with a whitish amorphous material. The relative propor- _ 
