1888 - 89 .] Mr Irvine & Dr Woodhead on Carbonate of Lime. 345 
the degenerated gland the separation takes place on one side of the 
membrane, and the deposition on the other, where there is a mass of 
dead albnmenoid material which readily takes up all the lime salts 
brought to it. That there is an outward current of certain material 
in the case of tubercular caseous masses enclosed in a fibrous capsule 
is extremely probable, from what we have observed in waxy disease 
associated with tubercle. 
The tendency to calcification in degenerated areas in the 
herbivorous animals has long been a subject of remark amongst 
comparative pathologists. This tendency is markedly exaggerated 
where the area is in any organ in which the tissue metamorphoses 
are specially active. For instance, in tubercle of the lung and 
udder in the cow, calcification follows caseation with remarkable 
rapidity, especially in the latter organ. In a case of acute miliary 
tuberculosis in the horse, for specimens of which we are indebted 
to Professor M‘Fadyean, this calcification has taken place at once, 
and the whole of the caseous material in the centres of most of 
the minute tubercular nodules are infiltrated with globular particles 
of insoluble lime salts. Around this central portion there are usually 
a few hyaline-looking cells, which have evidently taken the place of 
the fibrous tissue as a dialysing membrane, and outside this again we 
have the actively proliferating granulation tissue characteristic of 
this process. It is a well-known fact that in febrile conditions in 
Man and in the Carnivora, wdiere there is an increase in tissue 
metabolism, indicated by the rise of temperature of the blood, there 
is always, or usually, an increase in the amount of triple phosphate 
of lime, magnesia, and ammonia deposited in the urine. Under 
similar circumstances, in the Herbivora, on the other hand, we have 
an increase in the quantity of carbonate of lime, frequently in the 
form of peculiar dumb-bell shaped crystals, deposited after the 
urine is passed. In both cases the increased activity of the tissues 
leads to an increased evolution of carbonic acid, and we have a 
beautiful experiment in nature corresponding to our experiments 
relating to the precipitation of phosphate and carbonate of lime 
from a solution of phosphate of lime and alkaline carbonates, 
the proportions of the two salts precipitated, varying according 
to the relative amount of phosphoric and carbonic acid present. The 
tissues here playing the part of carbonic acid formers in the process. 
