1888-89.] Mr Irvine & Dr Woodhead on Carbonate of Lime. 335 
The existence of alkaline phosphates would appear to preclude the 
presence of soluble carbonate of lime in any quantity in the blood, as 
when brought together in solution these salts react upon one another 
with the formation of insoluble phosphate of lime and carbonate of 
soda. Therefore, even if this change is not effected in the primary 
processes to which blood formation is due, it must take place at 
that point when the incepted lime compound (be it what it may) 
becomes part and portion of the blood. 
That phosphoric acid combined with alkalies and alkaline earths 
plays an important part in the functions of the blood, and in tissue, 
bone, and shell formation, there can be no doubt. We find, both in 
the case of birds and crabs experimented upon by us, comparatively 
large and constant quantities present, which seem to have no parti- 
cular ratio to what they absorb from their food or sea water, but 
rather depend upon the part this acid plays acting as a carrier of 
the lime as phosphate or phosphatic albuminate to the required 
point where it is to be transformed in the presence of nascent car- 
bonic acid (or carbonates) into carbonate of lime, the phosphoric acid, 
especially during the period of active growth of new shell formation 
following ecdyses, meantime not passing out of the body to any 
extent but re-entering the circulation to continue to assist in the 
process of elaboration of lime salts. 
If a solution of carbonate of lime and phosphate of soda in 
carbonic acid be heated to 90° F., we find that there is a deposi- 
tion of phosphate of lime with a comparatively small propor- 
tion of the carbonate, the proportion of this depending upon the 
relative amount of alkaline phosphate present. If these salts could 
be removed as they are formed, and in the proportions in which 
they are thrown down, it would appear that we should have just 
those proportions that we get deposited in the matrix of bone. We 
shall have occasion to show that we consider that there is actually 
a dialysis of these lime salts into the formed material in which they 
are found deposited. 
Let us take, for example, developing bone in any animal. There 
are several factors to be taken into account in connection with the 
deposition of lime salts to bring about the calcification of bone. 
We have, in the first place, the presence of alkalies and alkaline 
earths in the blood of animals, combined with phosphoric acid and 
