342 Proceedings of Royal Society of Edinburgh. [sess. 
As regards the proportion of the lime salts and chitin, Schmidt* 
found that the amount of earthy phosphate increases in proportion to 
the quantity of chitinous tissue present in the basement structure : — 
Crawfish. 
Squilla. 
Lobster. 
Chitin, 
46*73 
62-84 
22-94 
Lime Salts, . 
53-27 
37-17 
77-06 
100-00 
100-00 
100-00 
Phosphate of Lime, 
13-17 
47-52 
12-06* 
Carbonate, 
86-83 
52-48 
87-94 
100-00 
100-00 
100-00 
He argued from this that the phosphate of lime is in intimate 
relation with cell-formation. We should he inclined to say 
rather, that as the chitin becomes older and thicker the cellular 
layer becomes less active, less carbonate is formed, and that there 
is thus a more direct passage outwards of the phosphate. 
From a careful examination of the conditions under which calci- 
fication occurs in pathological processes in the human and other 
subjects, we have come to the conclusion that this process of 
dialysis plays a most important part in the separation of the lime 
salts from the lymph and their deposition in degenerated tissues. 
First, there is in every case most serious interference with the 
vitality of the tissues in which calcification takes place. 
We have already seen that lime salts are deposited in the 
formed and inanimate matrix. In cartilage the same thing occurs, 
and in some cases the calcification is found even in the hard cell- 
membrane of the cartilage cells. Lime is never found as a deposit, 
visible under the microscope, in living protoplasm, except near the 
surface of epithelial secreting cells, hut it is frequently found in 
the formed material of cells both when it remains part of the cell 
and when actually separated, as where a matrix is formed. 
As further examples of this deposition in matter in a state of 
degeneration, we may take such a condition as atheroma of an 
artery, in which, during the earlier stages of the disease, w T e have 
a low inflammatory condition due to altered nutrition of the tunica 
intima followed by fatty degeneration, and lastly, by extreme calci- 
* Loc. cit., p, 22. 
