554 TISSUES OF THE CONNECTIVE SUBSTANCE. 



Bone Marrow. We differentiate between the red and yellow mar- 

 row, to which also belongs the gelatinous marrow, poor in fat, found in 

 fat atrophy and in old age. The difference between the first two-men- 

 tioned kinds of marrow lies, essentially, in the fact that the red marrow 

 contains a greater quantity of erythrocytes besides a higher content of 

 protein and less fat. The fat of the yellow marrow is, according to 

 NERKING/ richer in oleic acid and poorer in solid fats than the fat of the 

 red marrow. Besides the fat, lecithin also occurs in the bone-marrow 

 and this varies in amount in different animals and at various ages, as 

 mentioned on page 244. The protein consists of a globulin coagulating 

 at 47-50 C. (FORREST) and a nucleoprotein with 1.6 per cent phos- 

 phorus (HALLIBURTON 2 ) besides fibrinogen (P. MULLER 3 ) , traces of 

 albumin and proteose. In the extractives are found lactic acid, inosite, 

 hypoxanthine, cholesterine and bodies of an unknown kind. The quan- 

 titative composition of both kinds of marrow varies considerably with 

 the fat content, and the reports of the different investigators are corre- 

 spondingly discrepant (NERKING, HUTCHINSON and MACLEOD 4 ). 



The diverse quantitative composition of the various bones of the 

 skeleton depends probably on the varying quantities of other tissues, 

 such as marrow, blood-vessels, etc., which they contain. The same 

 reason explains, to all appearances, the larger quantity of organic 

 substance in the spongy part of the bones as compared with the more 

 compact parts. SCHRODT S has made comparative analyses of different 

 parts of the skeleton of the same animal (dog) and has found an essen- 

 tial difference. The quantity of water in the fresh bones varies between 

 138 and 443 p. m. The bones of the extremities and the skull contain 

 138-222, the vertebra 168-443, and the ribs 324-356 p. m. water. The 

 quantity of fat varies between 13 and 269 p. m. The largest amount 

 of fat, 256-269 p. m., is found in the long tubular bones, while only 

 13-175 p. m. fat is found in the small short bones. The quantity of 

 organic substance, calculated from fresh bones, 'was 150-300 p. m., and 

 the quantity of mineral substances 290-563 p. m. Contrary to the 

 general supposition the greatest amount of bone-earths was not found 

 in the femur, but in the first three cervical vertebrae. In birds the 

 tubular bones are richer in mineral substances than the flat bones 

 (DURING), and the greatest quantity of mineral bodies has been found 

 in the humerus (HILLER, DURING 6 ). 



1 Bioch. Zeitschr., 10. 



2 Forrest, Journ. of Physiol., 17; Halliburton, ibid., 18. 



3 See footnote 1, p. 253. 



4 Nerking, 1. c.; Hutchinson and Macleod, Journ. of Anat. and Physiol., 36. 

 6 Cited from Maly's Jahresber., 6. 



"Killer, cited from Maly's Jahresber., 14; Diiring, Zeitschr. f. physiol. Chem., 23. 



