124 FORMATION OF SHELLS OF ANIMALS, ETC., 
denser parts of this organ. The piece of lamina spiralis 
thus perforated has the appearance of a fragment of a 
foraminiferous animalcule. -This form of lacuna seems to 
arise simply from the thickness of the plate of bone at this 
part being less than the transverse diameter of an ordinary 
lacuna, so that organs like these, complete in all their 
dimensions, would have, in such situations, presented a 
number of bulgings on the surface of the osseous lamina, 
instead of rounded or oval spaces penetrating entirely 
through it. Now, if the function of these parts had been 
of vital importance, is it not more probable that they 
would have retained their integrity at so apparently 
inconsiderable a sacrifice, than that they would have been 
thus mutilated? Perhaps the identity of these foramina 
with lacunze will not be admitted ; then, as there is nothing 
else connected with these plates of bone which can be 
taken for bone-cells, the only conclusion to be arrived at 
would be that they were formed without the instrumentality 
of any such organism ; and thus fresh testimony would be 
added to that which has been already adduced, to prove 
that the form of osseous tissue, called by physiologists 
lacune or bone-cells, is not endowed with the vital power 
of forming bone, being itself a secondary and not a 
primary formation. Now, as the identity of these 
openings with true and perfect lacunz can scarcely be 
questioned, the last supposition is not likely to be generally 
maintained ; and as the improbability of their function as 
formative organs will be shown better by considering 
what lacune are, than what they are not, I will proceed 
to the consideration of what appears to me to be their use ; 
both as they exist in the form of foramina in the lamina 
spiralis, and as minute cavities elsewhere. Now bone, 
like every other form of organized tissue, is in no part of 
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