50 THE PHASES OF 



calcareous basis-substance. Such formations are absent in old 

 animals. 



Bone-corpuscles. In comparing bone-corpuscles of a newly 

 born with those of an old dog, a difference in the structure is 

 apparent. The cavities of the former contain a central globular, 

 oblong, or angular vacuoled lump of a yellowish color, and 

 intensely shining. Around this lump there is a pale, finely 

 granular protoplasm; the spokes springing from the central 

 lump blend with the pale protoplasm, or, in places where the 

 latter is apparently wanting, with the basis-substance of the 

 bone. We not infrequently meet with bone-cavities entirely 

 filled with the yellow, shining substance. (See Fig. 17.) 



In the bone of a dog, about ten years old, there are but few 

 corpuscles, with pale yellow shining nuclei ; whereas cavities 

 with pale protoplasmic bodies and pale nuclei largely prevail. 



FIG. 18. BONE-CORPUSCLES FROM A LONGITUDINAL SECTION OF THE 

 THIGH-BONE OF A DOG, EIGHT TO TEN YEARS OLD. 



P, corpuscle, with a vesicular nucleus ; B, basis-substance. Magnified 800 diameters. 



The latter represent gray, vacuoled lumps or vesicles, with one 

 to two yellow shining, or one to three gray opaque nuclei, 

 of which the former usually are larger than the latter. (See 

 Fig. 18.) 



Corpuscles of the Medulla of Bone. The medulla of bone also 

 exhibits marked differences of age. In the medullary spaces of 

 a shaft-bone of a new-born pup, the apparently homogeneous 

 basis-substance holds small, yellowish, shining lumps, either 

 globular or elongated, either homogeneous or vacuoled. Besides, 

 there are pale protoplasmic bodies with globular nuclei, similar 

 in aspect to the lumps just described ; also pale bodies are seen 

 without nuclei, but in their place cavities with one or two.opaque 



