THE OSSEOUS SYSTEM. 293 



this situation, whilst cells of the kind already described in the muscular 

 system ( 82), arranged in series, are not unfrequently met with, and 

 might perhaps be regarded as cartilage-cells, although their nuclei exhibit 

 the most evident indications of a transition into nuclear fibres. The 

 articular cartilages, moreover, during their development, which will be 

 entered into more particularly afterwards, have no nerves or vessels, as 

 is the case also with the cartilaginous lips.* 



The condition of the bone beneath the articular cartilages, requires 

 special notice. It consists, in almost all joints, in immediate contiguity 

 with the cartilage, of % a layer of incompletely formed bone-substance, 

 and, more internally, of that tissue in its usual form (Fig. 125). The 

 layer in question, which is 0-04-0-16, or on the average 0-12 of- a line 

 thick, is composed of a yellowish, mostly fibrous, hard, and truly ossified 

 matrix, containing, however, not a trace of Haversian canals or medul- 

 lary cavities, nor of any perfectly formed lacunae ; instead of which it 

 presents roundish or elongated corpuscles, aggregated into little masses 

 or rows, the larger of which are 0-0160-024 of a line in length, and 

 0-006-0-008 of a line in breadth, and the smaller 0-006-0-008 of a line 

 in length, and 0-004-0-005 of a line in breadth, which give thin sections 

 of the bone a perfectly opaque aspect, and consequently might be 

 regarded as bone-corpuscles (lacunae) filled with calcareous particles, as 

 which they have lately been considered by H. Meyer (1. c., p. 325, 326). 

 By the addition of spirit of turpentine, which, however, penetrates with 

 difficulty, this error is dissipated, and it is found, that as in the case of 

 the lacunae of dried bone, the opaque aspect is due only to the air con- 

 tained in them, and that the bodies in question are nothing more than 

 thick-walled cartilage-cells, retaining their contents (fat, nuclei), present- 

 ing occasionally indications of canaliculi, and perhaps also partly calci- 

 fied ; in other words, that they are undeveloped lacunae. The layer in 

 which these cells are lodged, and which, towards the cartilage, is bounded 

 by a straight line, occasionally dark from calcareous particles, and 



* [Besides the elements above mentioned, we find according to Dr. Leidy (see Am. Jour, of 

 Med. Sc., April, 1849), numerous minute lacunae, as an occasional peculiarity in the structure 

 of articular cartilage. These lacunae are described by Dr. Leidy as existing in greatest abun- 

 dance in the deeper part of the cartilage; but decreasing in number, as its free surface is ap- 

 proached. They are lenticular in outline, and measure from l-1200th-l-3 120th of an inch; 

 when well defined, they appear beneath the microscope more translucent than the cartilaginous 

 matrix in which they are situated. When viewed a little within the focus of the instrument, 

 they are of a deep black color, and oppose the transmission of all light. Another peculiarity de- 

 scribed by Dr. Leidy is the penetrature of the structure of the cartilage by fibres or columns 

 of bone. These fibres are quite uniform in shape and structure, being compressed and 

 cylindrical ; in transverse sections they present an elliptical figure. They are not numerous, 

 and vary from a size not exceeding a cell-group of 5 cells to the size of four or five such 

 groups. They are concentrically laminated, and also present a radiated conformation, resem- 

 bling somewhat the structure of an Haversian canal, but neither the canal nor the Purkin- 

 jean corpuscles are discernible in them. DaC.] 



