352 Proceedings of Royal Society of Edinburgh. [sess. 
When alkaline phosphates associated with lime and albumen pre- 
ponderate in the blood, the lime so separated is in the form of phos- 
phate, as in bone formation; when these are partially replaced by an 
excess of alkaline carbonates as in marine animals, the lime is secreted 
as carbonate. 
The corals have a secreting layer of cells similar in all essential 
features to the secreting layers above mentioned, and the products of 
their activity assume the same forms, chitin, chitin infiltrated with 
carbonate of lime, and almost pure carbonate of lime with a small 
quantity of organic cementing material. 
Carbonate of lime may be formed as follows : — 
The carbonate of ammonia produced by the decomposition of the 
effete products of animals, urea, &c., decomposes a portion of the 
sulphate of lime in the sea water with the formation of carbonate of 
lime equivalent in amount to the carbonate of ammonia thus formed. 
We take this opportunity of thanking Messrs Drysdale and 
Anderson, who, as chemists, attached to the Marine Station, 
Granton, gave us their hearty assistance during the period over 
which these investigations extended. 
APPENDIX. 
TABLE I. — Egg Shell (Hen’s). 
Dried at 212° F. Membrane removed. 
Salts added to Food. 
No. 1. 
Sulphate 
of Lime. 
No. 2. 
Phosphate 
of Lime. 
No. 3. 
■ Silicate of 
Lime. 
No. 4. 
Nitrate 
of Lime. 
No. 5. 
Carbonate 
of 
Magnesia. 
No. 6. 
Carbonate 
of 
Strontia. 
Hens laid Eggs. 
Normal. 
Normal. 
Normal. 
Normal. 
Shell-less. 
Shell-less. 
Analysis of Shell. 
Organic matter, 
6-86 
577 
About 
Same 
Carbonate of lime, . 
Phosphate of lime, . 
Sulphate of lime, 
Silica, 
Magnesia, 
Iron, 
92-03 
1-11 
trace 
y y 
93-07 
1-16 
trace 
y y 
same 
as in 
1 and 2. 
as in 
1 and 2. 
... 
