180 CONNECTIVE TISSUE. 



In longitudinal sections from the surface of a shaft-bone of 

 the same animal, we see in the periosteal tissue different forma- 

 tions corresponding to the stages of development of protoplasma. 

 Between longitudinal bundles of narrow, bright ribbons we 

 recognize fields of corpuscles like those of the medullary tissue, 

 or chains of such corpuscles with distinct vesicular nuclei. Fur- 

 thermore, we see fields of flat, spindle-shaped protoplasmic bodies 

 of greatly varying size, and with either indistinct nuclei or none. 

 There are fields composed of flat, rhomboidal protoplasmic 

 bodies, some of which exhibit formations like nucleoli. We also 

 meet with fields, the rhomboidal bodies of which appear homo- 

 geneous, and slightly shining. Lastly, we encounter ribbons 

 and ledges, composed of very much elongated rhombs, character- 

 ized by a peculiar yellowish color and a considerable luster. The 

 slightly shining fields are the connective-tissue ribbons proper of 

 the periosteum ; while the highly refracting ribbons and ledges 

 are termed elastic. (See Fig. 70.) 



The examination of good chromic acid specimens, better still 

 such specimens slightly stained with chloride of gold, convinces 

 us that each larger field is separated from the neighboring fields, 

 and within the fields each granular or homogeneous corpuscle from 

 the neighboring corpuscles, by a narrow light rim, which is invari- 

 ably traversed by delicate grayish spokes. Even in the narrow 

 elastic ribbons a faint transverse striation is here and there seen. 



In such a specimen, deeply gold-stained, the differentiation of 

 fields and ribbons disappears, and there become visible at certain 

 intervals spindle-shaped, dark violet bodies, corresponding to the 

 protoplasmic bodies, while the rest of the tissue is split up into a 

 reticulum, with either fine or coarse granules as nodular points. 



The periosteal tissue is composed of narrow, spindle-shaped 

 fields, wherever it exhibits a striated or fibrous appearance. In 

 portions made up of broad ribbons, on the contrary, each field 

 represents an elongated rhomb, in which lie, at pretty regular 

 intervals, oblong, flat, nucleated protoplasmic bodies (the " peri- 

 osteum cells"). Between the rhombs are narrow, bright ledges, 

 the elastic fibers, which either connect several rhombs into large 

 bundles, or subdivide a single rhomb into smaller rhomboidal 

 fields of varying size. At the corners of the rhombs the elastic 

 fibers are interconnected with acute angles. 



If, owing to a laceration of the tissue with the razor, a 

 broader, slightly shining ribbon projects from the border of the 

 specimen, we often see at its edge, either on one side or on 



