2(J STRUCTURE AND GROWTH 



dark side in the thickness of the walls distinguished. The 

 delineation, at the same time, proves how important a share is 

 taken by the intercellular substance in the formation of the 

 firm structure of cartilage. 



The cartilages of the foetus do not altogether accord in chemi- 

 cal constitution with those of the adult, since we can obtain from 

 them by boiling but a small quantity of a gelatinous substance, 

 and that only with great difficulty, and they afford no true 

 gelatine (capable of forming a jelly). I boiled some unossi- 

 fied cartilages, consisting of apophyses of the femur and carti- 

 laginous portions of the scapulae, taken from several embryo 

 pigs, measuring three and a half inches in length. After 

 twelve hours' boiling, they entirely crumbled into very small 

 scales, which gave a variegated appearance to water in which 

 they were stirred about, and appeared under the microscope 

 extremely thin and granulous. The fluid, when filtered and 

 evaporated almost to dryness, did not coagulate. Alcohol pro- 

 duced a copious precipitate, wTiich was dried, afterwards dis- 

 solved in boiling water, and then evaporated almost to dryness; 

 still no coagulation took place. Alum, however, clouded the 

 fluid, and acetic acid had the same effect, but in a much 

 slighter degree. As the quantity of cartilage made use of in 

 the foregoing experiment was too small, I made a further in- 

 vestigation with cartilage which had already become ossified, 

 from the same embryos, namely, the frontal and parietal bones, 

 scapulae, humerus, femur, and some ribs. The unossified parts 

 were removed as cleanly as possible from all the bones. The 

 earthy matter was withdrawn by hydrochloric acid; the carti- 

 lages were then washed with water, and boiled for twenty-four 

 hours. Under this process they fell to pieces very slowly , 

 meanwhile numerous little glittering scales appeared in the 

 fluid, which, after being dried, resembled very minute fish- 

 scales, and exhibited a beautiful play of colours. They were, 

 perhaps, the lamellae described by Deutsch, which surround the 

 minute medullary canaliculi. The form of most of the pieces 

 of cartilage remained perfectly recognizable, and was but 

 slightly altered. They looked of a yellowish-white colour, and 

 not at all gelatinous, as substances usually do when about to 

 be transformed into gelatine. The fluid was filtered from these 

 little scales and pieces of cartilage, and then evaporated almost 



