THE OSSEOUS SYSTEM. 311 



fluid, in all the red, or even only reddish marrow {never in .the 

 yellow), minute roundish, nucleated cells, exactly like those of 

 the young medulla (vid. infra, fig. 132). These medulla-cells 

 correspond in every particular with those, which Hasse and I 

 (' Zeitsch. f. ration. Medicin/ Bd. V) found in the hyper- 

 amiiated red marrow of the articular extremities of the 

 cylindrical bones, but nevertheless normally exist in the 

 rcrtebrce, the true cranial bones, in the sternum, and in the 

 ribs, whilst they are wanting in the long and short bones of 

 the extremities, and. in the scapula and os innominatum, 

 occurring apparently in variable number in the bones of 

 the face. 



§9!. 



Connections of the Bones, — A. synarthrosis, connection 

 without articulation. 



1. By suture. In this mode of connection, the bones are 

 united by an extremely thin, membranous, whitish streak, to 

 which authors have incorrectly given the name of sutural car- 

 tilage. It is composed merely of connective tissue, which, like 

 that of the ligaments, extends, in short, parallel fasciculi, from 

 the border of one bone to that of the other, and is characterised 

 solely by the presence of numerous, short, unequal-sized, 

 usually elongated nuclei. This sutural liyament, as it may be 

 termed, is very evident as long as the cranial bones are still 

 growing, at the same time, that it is softer and differently 

 constituted [vide infra). As the growth of the cranium ap- 

 proaches its completion, this tissue gradually disappears, be- 

 comes firmer, and, in old age, seems, in many places, especially 

 on the inner part of the sutures, and even before their complete 

 obliteration, to be entirely removed. 



2. Connection by ligament, syndesmosis, is effected by means 

 of fibrous and elastic ligaments. The fibrous ligaments, consti- 

 tuting the majority of the ligaments, are white and glistening, 

 corresponding in their structure, partly with the aponeuroses 

 and ligaments of the muscles, and partly with the true tendons. 



Elastic ligaments (fig. 121), are, the ligamenta flava, between 

 the arches of the vertebrce, and the Ugamentum nucha, which, 

 however, is not nearly so well developed in man, as in some 

 others of the Mammalia. The ligamenta flava are yellowish, 



