TRANSACTIONS OF SECTION D. 637 



in Sowerby's whale, fewer in Ilyperoodon rostrates, and, according to our observa- 

 tion, present as a single small cavity only in the narwhal. 



The division is followed by the single pyloric cavity, according to Turner, but 

 in the narwhal by two divisions, both of which are lined by ' pyloric ' mucous mem- 

 brane. Until we have a most careful examination of the mucous membrane from 

 different parts of all the cavities in the various species, it will evidently be unsafe 

 to generalise too widely, as from what we have observed we cannot bring the 

 stomach of the narwhal entirely under the classification given by either Turner or 

 Max Weber. """*' 



10. On the Secretion of Carbonate of Lime by Animals. 

 By Robert Irvine, F.C.S., and G. Sims Woodhead, M.D. 



liens supplied witli any salt of lime produce normal egg-shells composed of 

 carbonate of lime. They cannot make shells from magnesium or strontium carbon- 

 ate. Crustacea, such as crabs, cannot assimilate sulphate of lime from the sea-water 

 to form their exo-skeleton. They can form their shells from calcium chloride. 



In the egg-shell, the organic and inorganic material are both secreted by cells 

 separated from the epithelial cells. In the crab-shell the organic material (chitin) 

 remains attached to the epithelial cells, and in this the lime salts are deposited, 

 probably by a process of dialysis, whilst in the case of bone, the cells are not 

 epithelial in character, the matrix though separate is closely associated with the 

 cells, especially during its formation, aud the lime is deposited in the matrix ap- 

 parently by a process of dialysis. Phosphoric acid, combined Avith alkalies and 

 alkaline earths acts as the carrier of the lime salt to the secreting cells. "NMiile in 

 the blood the lime salt is as a phosphate ; it may be thrown out mostly as carbonate 

 on meeting nascent carbonic acid at the secreting cells. 



Lime salts, of whatever form, are deposited only in vitally inactive tissue such 

 as bone matrix, chitin, or tissues that have undergone degeneration. Although the 

 tissue be dead deposition may go on. 



Carbonate of lime may be formed in sea-water as follows : the carbonate of 

 ammonia produced by the decomposition of the effete products of animals, urea, 

 etc., decomposes a portion of the sulphate of lime in the sea-water with the for- 

 mation of carbonate of lime equivalent in amount to the carbonate of ammonia 

 thus formed. 



11. On the Solubility of Carbonate of Lim,e in Fresh and Sea Water. 



By W. S. Anderson. 



Mr. Anderson stated that during last winter he had, at the request of Dr. Murray 

 of the ' Challenger ' expedition, continued the investigation of Messrs. Irvine 

 and Young on the solubility of carbonate of lime in its different forms in sea-water. 

 Special attention had been given to the solubility of amorphous and artificially 

 crystallised carbonate of lime, and the various forms of coral in sea-water. The 

 results showed that crystallised carbonate of lime was somewhat more soluble 

 in pure water than in sea-water, and that amorphous carbonate of lime was more 

 soluble in sea-water than in pure water. When sea-water stood over crystallised 

 carbonate of lime for a lengthened period it first dissolved and then re precipitated 

 it again. This was supposed to be an agent in the petrifaction of the porous masses 

 of coral reef. The soluble action of sea-water on carbonate of lime was independent 

 of any carbonic acid present, for an artificial sea-water free from carbonic 

 acid would dissolve as much whether crystallised or amorphous. The action was 

 limited to the saline constituents of the sea-water. The action was simply that of 

 solution, not of chemical change into sodium carbonate and calcium chloride. The 

 soluble action of each constituent, water and salts, when taken together showed 

 that the surplus base already present in sea- water need only be the single carbonate 

 of lime and not the bi-carbonate. 



