CASEATION 385 



diffuse readily from the bodies of the bacilli. Comparison of the 

 chemical composition of bovine and human tuberculous lesions witli 

 the corresponding normal tissues by Caldwell'^ gave the following 

 results: 



The tubercle walls and the caseous material from lymph gland tubercles contain 

 a lower percentage of water than does the normal tissue. In normal bovine liver 

 tissue, the percentage of water present is less than that of the tubercle walls or of 

 the caseous material from liver tubercles. The specimens of oasQous material 

 from lymph gland and liver tubercles approach each other closely in their water 

 content, the average being about 75% for the bovine material. 



The alcohol-ether-soluble substances from normal bovine lymph glands form 

 about 24.4% of the dry weight, or about 4.4% of the moist weight. The walls of 

 the lymph gland tubercles contain a distinctly larger amount of lipins than does 

 the caseous material or the normal tissue. On the contrary, the walls of liver 

 tubercles are poor in lipins as compared with the normal tissue, and they contain 

 a smaller amount of fats than does the caseous material from these tubercles. 

 When calculated on the basis of the dry weight, the caseous material from lymph 

 gland tubercles contains a smaller percentage of lipins than does normal lymph 

 gland tissue. When the ash is deducted, this difference disappears and the 

 content of lipins becomes equal to or slightly greater than that of the normal 

 tissue, but less than that of the tubercle walls. When calculated on an ash-free 

 basis, the lipin content of the caseous material from liver tubercles is distinctly 

 less than that of the normal tissue but greater than the lipin content of the tubercle 

 walls. 



Cholesterol forms about 6.5% of the lipins from normal bovine lymph glands, 

 or about 1.5% of the dry weight. The lipins from the walls of lymph gland and 

 liver tubercles contain, in every case, 2-3 times as much cholesterol as do the lipins 

 from the normal tissues. This is an actual increase also when calculated on the 

 basis of the dry weight. The caseous material contains even a larger percentage 

 of cholesterol than do the tubercle walls. Phospholipins constitute about 32% 

 of the lipin fraction of normal bovine lymph glands, or about 7.9% of the dry weight; 

 the corresponding values for normal liver are 41.2% of the fats, or 14% of the dry 

 weight. The phospholipin content of the fats from the tubercle walls is slightly 

 less than that of the normal tissues, while there is a very marked reduction in the 

 phospholipin content of the lipins from caseous material of bovine origin. In 

 the specimen of caseous material from human lymph glands, phospholipins formed 

 30.9% of the total lipins. The iodin numbers obtained from the fats of the tuber- 

 culous specimens from lymph glands are higher than those from the normal tissues. 

 This observation does not hold true for the liver specimens. In the latter, there is 

 no difference noted between the iodin numbers obtained for the lipins from normal 

 and tuberculous specimens, although the values are practically the same as those 

 from the fats from the lymph gland tubercles. 



In the residues of caseous material left after extraction with alcohol and ether 

 the nitrogen content remains relatively high; in fact, the reduction in nitrogen 

 content is only slight when the calculations are made on ash-free residues. The 

 percentage of nitrogen does not differ much from that obtained from the normal 

 proteins of these tissues. In specimens of caseous material in which there are no 

 macroscopic evidences of calcification other than the presence of sandlike particles, 

 calcium sometimes forms as much as 15% of the residue left after extraction of the 

 fats. In such residues, the phosphorus content may reach 9%. 



The amount of purine nitrogen in the walls of lymph gland tubercles is only 

 slightly more than iiali that of normal lymph gland tissue, and the amount is 

 apparently much less in the caseous material. In the residues from the walls of 

 liver tubercles, purine nitrogen is present in only slightly higher percentage than in 

 the normal liver. The results here obtained would seem to indicate that the pur- 

 ines are even more abundant in the caseous residues of liver tubercles. The 

 amount of material which enters the water solution during extraction is distinctly 

 less from caseous material than from the residues of normal tissues. 



" Jour. Infect. Dis., 1919 (24), 81. Full review on composition of tuberculous 

 tissues. 



25 



