120 TISSUES IN GENERAL. 



Tissue of the Umbilical Cord. Longitudinal sections of the 

 human umbilical cord, hardened in a chromic acid solution, 

 exhibit, as is well known, a striated or fibrous structure. The 

 fibers are densest at the periphery of the cord and around the 

 blood-vessels, and these layers are interconnected by a relatively 

 coarse reticulum of fibers, the meshes of which contain a homo- 

 geneous substance. In the fibrous layers we meet with large, 

 nucleated, freely branching protoplasmic masses, also with 

 smaller, spindle-shaped bodies, and with very small protoplasmic 

 cords and lumps, devoid of nuclei. In the mesh-spaces, traversed 

 by a few fibers which the cutting has partly torn, we encounter 

 apparently isolated globular corpuscles, having one or several 

 nuclei, but no offshoots.* The amount of living matter in the 

 protoplasmic bodies is variable. We find compact lumps char- 

 acterized by a nearly homogeneous structure, considerable luster, 

 and yellow color; furthermore, coarsely and finely granular 

 corpuscles, with either homogeneous, shining, or finely granular 

 pale nuclei, some containing nucleoli; lastly, very pale, deli- 

 cately granular bodies destitute of both nuclei and a marked 

 boundary line toward the basis-substance. The periphery of all 

 these corpuscles, while they are in connection with the tissue, 

 looks more or less scalloped or thorny, and the same is the case 

 with their nuclei. 



Upon rubbing a fresh umbilical cord with a stick of nitrate of 

 silver, and exposing the specimen, kept in water, to the daylight, 

 it will soon become brown, t 



Longitudinal sections of an umbilical cord colored in this 

 way exhibit, even with lower amplifications, numerous many- 

 shaped light and colorless fields in the brown basis-substance. 

 High amplifications demonstrate that the light fields in different 

 directions send branches into the basis-substance, f and that from 



*For reference: Rud. Virchow's " Cellularpathologie," 4 Aufl., 1871. 

 Weisman, "Zeitschrift fiir rat. Mediz." 3 Reihe, Bd. xi., 1861. K. Koster, 

 "Ueber die feinere Structur der menschl. Nabelschnur," Wiirzburg, 1868. 

 Koster found the globular corpuscles in the mesh-spaces, and the spindle- 

 shaped cells near the spaces without fibrils, to be amoeboid. 



t Method of F. von Recklinghausen ("Die Lyinphgefasse und ihre Bezie- 

 hung zum Bindegewebe." Berlin, 1862). Specimens containing black, 

 granular precipitations I consider as useless. The features described can be 

 observed only when the basis-substance is stained light or dark brown, and 

 the fields corresponding to the protoplasmic bodies are colorless. 



t Koster (I. c.), by means of the silver tinction, brought to view the larger 

 light fields only. 



