CHAP. II.] 



THE CAT 8 GENERAL FORM. 



1!) 



does not contain blood-vessels, but can yet grow rapidly, the nuclei of 

 the cells multiplying and the cells and corpuscles themselves enlarg- 

 ing and dividing the homogeneous matrix coming to occupy the 

 intervening space as the capsules divide and separate. 



5. BONE, or osseous tissue, is a substance, two-thirds of which, in 

 the cat, consists of mineral matter namely, of phosphate with 

 some carbonate of lime, and a very little fluoride of calcium, phos- 

 phate of magnesia and common salt. The animal * and mineral 

 parts are absolutely united, since by the elimination of either, tho 

 shape of the bone remains unaltered. 



Compact bone, such as that which forms the thigh-bone of the 

 cat, exhibits on its surface a number of microscopic holes, which are 

 the external apertures of canals, called " ffaversian," which thence 



Fig. 5. SECTIONS OF CAT'S LEG-BONE, GREATLY MAGNIFIED. 



The right-hand figure shows the layers arranged 

 concentrically around the Haversiau canal. 



The left-hand figure shows a section nearly in 

 the plane of such a canal. 



h. Haversian canal. 

 I. Lacunae, 

 c. Canaliculi. 



enter and ramify. These holes and canals serve to admit blood- 

 vessels. The bony substance forms concentric layers about such 

 canals, while the layers themselves contain a number of irregular 

 radiating spots, which are also arranged in concentric rings corre- 

 sponding with the layers in which they lie. These spots are inter- 

 spaces called "lacunae," (and sometimes "bone corpuscles,") and 

 their outline is so irregular because each gives off a number of 

 minute tubular processes, termed canaliculi. The canaliculi of 



* This substance when boiled yields 

 gelatine. Cartilage yields chondrin, 

 which differs somewhat from gelatine in 

 its chemical relations ; but, like it, dis- 

 solves in hot water, and forms a jelly on 



cooling. Connective tissue also yields 

 gelatine when boiled, but elastic tissue 

 does not. The latter tissue is also (as 

 before said) unaffected by acetic acid. 



c 2 



