344 Proceedings of Royal Society of Edinburgh. [sess. 
calcification had only just commenced, we found that by far the 
larger proportion of cretaceous material was present as minute hard 
points immediately beneath the fibrous capsule. In fact, when the 
gland was cut in two, the caseous mass could be completely 
“shelled out” from the dense fibrous capsule. On the surface of 
the central mass were small concretions, each of which appeared to 
fit into a corresponding depression in the capsule. Examining the 
centre of the mass, a far less proportion of lime was found than 
at the periphery. Here then is a fact favouring our view that 
dialysis plays a most important part in the separation of lime salts 
from lymph and their deposition in bone. An analysis of the solid 
portions of this gland gave the following results. After washing 
away the softer central caseous matter, the remainder, 124 '60 
grs., was ignited, by which there was lost 11143 grs., leaving 
1347 grs. or 1 0 *6 1 per cent, of ash. 
This Ash consisted of Phosphate of Lime, . . 81*26 
Carbonate of Lime, . . 14*31 
Salts, .... 4*61 
100*00 
It will be seen at once from this analysis that the proportion of 
carbonate of lime is considerably greater than in the bones of 
cattle, in which the proportion on the above calculation would be 
as 81*26 phosphate to 9*85 of carbonate. 
It is to be borne in mind, however, that there is usually a large 
area of granulation, or small cell tissue, around the fibrous layer, 
and that consequently the conditions approach more nearly the 
secreting surface of the oviduct of the hen say, where we have the 
thick layer of secreting protoplasm with the evolution of a consider- 
able amount of carbonic acid. There is, however, a considerable 
proportion of phosphate of lime directly separated and deposited, 
not in the fibrous layer in the first instance, but in the dead tissue 
beyond it. 
The process here differs somewhat from the allied process in bone, 
in this respect, that in bone there is the separation always taking 
place from two surfaces of the trabeculae, the deposit appearing in 
the middle and gradually extending outwards, whilst in the case of 
