342 SPECIAL HISTOLOGY. 



partially or not at all in contact with each other. The 

 contents of only a very few cells were still in the opaque 

 condition, and these were without any visible nucleus, 

 others exhibited the commencement of transparency from 

 the metamorphosis of their contents. The further develop- 

 ment of the cartilage up to the end of foetal life, except in 

 its ossification, presents these characteristics, viz. : (1.) That 

 the cells, precisely like those iu the batrachian larva, continually 

 increase by endogenous cell-formation, whilst precisely as in 

 the same instance, there is no indication whatever afforded, of 

 the production of cells, independently of those already in existence ; 

 and (2.) That the interstitial substance, which in this case is 

 manifestly formed, for the greater part, independently of the 

 cell membranes, is always increasing. With respect to the 

 cells, they are, iu the second costal cartilage of a four-month 

 foetus, according to Halting, OOOSG'" long, 00023'" wide, and 

 consequently their aggregate bulk pretty nearly corresponds 

 with that of the interstitial substance. In the embryo of 

 the Pig, 3 - 5'" long, the space occupied by the nucleated, clear, 

 thin walled cells, is, according to Schwann, thrice as great as 

 that taken up by the interstitial substance. In a five-months' 

 human embryo, I have myself noticed the cartilage cells, - 003 

 — - 008'" in diameter, with and without secondary cells, some 

 with, and some without distinct walls, and separated from each 

 other by a perfectly homogeneous substance 0002 — 0*005'" 

 thick. In the new-born child they measure, according to 

 Harting, 0-032-— 002S m m in length, and 00072 ra m - in breadth, 

 and are three or four times as numerous as in the foetus at four 

 months • but on the other hand, they occupy considerably less 

 space, proportionally, than the interstitial substance, the bulk 

 constituted by which is more than double that of the cells. 

 After birth, in the non-ossifying cartilages, the interstitial sub- 

 stance and the cells increase in pretty nearly an equal ratio, so 

 that their relative proportions in the adult are about the same 

 as in the infant at birth. In the adult the cells are from 8 to 

 12 times larger than in the new-born child (Harting), but, 

 according to him, their number is diminished, so that they 

 amount to not more than half of what existed in the child, 

 which is explained upon the supposition of a coalescence of the 

 cells. The numbers given by Harting do not appear to me 



