216 ANIMAL AMIDES. 



4. Elastic membranes ; for example the ligamenta flava of the 

 falx, the ligamentum hyothyroideum and cricotliyroideum me- 

 dium of the larynx, the ligaments of the larynx connected with 

 the voice, the middle coat of the arteries, &c. when hoiled suffi- 

 ciently long in water, give a glue possessed of peculiar charac- 

 ters ; but approaching nearer chondrin than collin. These mem- 

 branes have a yellow colour. They consist of fibres full of knots 

 and running into each other. They may be kept for years in 

 alcohol without losing their elasticity. 



The glue from them is precipitated by acetic acid and acetate 

 of lead, though not to the same degree as chondrin. It is pre- 

 cipitated also by alum and sulphate of alumina. But persulphate 

 of iron does not occasion a precipitate, it only renders the liquid 

 opal coloured. 



5. Fibrous cartilages, such as the cartilaginosiinarticulares, those 

 of the inter vertebral cartilages, those of the eyelids, likewise the 

 semilunar cartilages of the knee-joint of the sheep, give collin. 



6. The spongy cartilages, viz. the cartilages of the ear, the 

 epiglottis, the appendages to the cartilagines arytenoidece in cat- 

 tle and swine, give various kinds of gelatin. 



That from the cartilages of the ear differs from collin and 

 chondrin in this important respect, it does not gelatinize. The 

 glue obtained by boiling the sound of the cod also refuses to ge- 

 latinize, but dries into a hard brown substance, which may be em- 

 ployed to glue pieces of wood together. In chemical properties 

 the glue from spongy cartilages agrees with chondrin, excepting 

 that it is scarcely precipitated by acetic acid. 



7. Permanent cartilages, such as those that attach the ribs to 

 the sternum or to each other, the cartilages of the joints, Sec- 

 yield chrondrin, 



8. The cartilages of bones, obtained by removing the bone- 

 earth by an acid, yield collin, A great many were examined 

 by Miiller, and all yielded collin. Yet the same cartilages be- 

 fore ossification has taken place yield chondrin. It appears from 

 this that during ossification a change in the cartilaginous struc- 

 ture takes place* What tliis change is we have at present no 

 notion. 



9* Permanent cartilages ossified by disease, yield collin. 

 10.. The cartilages of the teeth yield collin. 

 H. Fungous bones yield chondrin* 



