BY MOLECULAR COALESCENCE. 113 
of air. These small globular portions are well seen in de- 
calcified specimens. I have such specimens showing these 
facts. I may observe, also, that the examination of the 
decalcified shell of pinna perfectly agrees with the fact just 
demonstrated, namely,that its component globules are made 
up of earthy matter, and animal basis molecularly com- 
bined, and not of cells formed first and afterwards filled 
with the former material. In the shell perfectly deprived 
of its component earthy constituent by hydrochloric acid, 
the appearance is so little altered, that were it not for the 
evidence afforded by the polariscope, the fact of its decalci- 
fication might be doubted. The portions of animal residua 
perfectly retaining their convexity, and their distinction of 
dark and light parts, when viewed by transmitted hght, 
show that something is left which had been in intimate 
union with the carbonate; but, as a matter of course, 
these appearances are less marked than before. There is 
no appearance of distinct cell-walls in these globules, 
when no pressure is made upon them; however, when 
pressed together, their exterior denser layers, which owe 
that density, as a natural consequence, to the mechanical 
forces concerned in their formation, may be forced one 
over another, and thus made to present the appearance of 
a cluster of compressed cells. As for the presence of 
nuclei, or the germs of cells in these residua, I 
may have seen something as characteristic as the gra- 
nules represented in p. xvi, figs. 2 and 10, of ‘The 
College Catalogue, but I am not aware that I have ; 
however, if I had seen such granules, or even some much 
more defined and regular in their form, I should have 
required evidence much more clear than has yet been 
adduced, before I could be convinced that each of these 
granules is endowed with the power of constructing a 
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