36 



COMPARATIVE ZOOLOGY. 



are condensed into sheets or parallel cords, having a wavy, 

 glistening appearance. Such structures are the fasciae and 

 tendons. Connective tissue is not very sensitive. It con- 

 tains gelatine — the matter which tans when hide is made 

 into leather. In this tissue the intercellular substances 

 take the form of fibres. The white fibres are inelas- 

 tic, and from -own- to of an inch in diameter. 

 They are best seen in the tendons. The yellow fibres are 

 elastic, curled at the ends, very, long, 

 and from -^two- to 40V0- of an inch in 

 diameter. They are shown in the 

 hinge-ligament of an Oyster. Connec- 

 tive tissue appears areolar, i. e., shows 

 h interspaces, only under the microscope. 

 Diagram: a, cartilage (3) Cartilaginous Tissue. — This tissue, 



cell; &, cell about to di- , 



vide ; c, cell divided into known also as "gristle, is composed 



two; d, into four parts. n • i i 1 i • i i 



The space between the oi cells imbedded in a granular or hy- 

 ^^^Zl ^ substance, which is dense, elastic, 

 stance; highly magni- bluish white, and translucent. It is 



fled. ' 



found where strength, elasticity, and 

 insensibility are wanted, as at the 

 joints. It also takes the place of the 

 long bones in the embryo. When 

 cartilage is mixed with connective tis- 

 sue, as in the ear, it is called fibro-car- 

 tilage. 



fc (4) Osseous Tissue. — This hard, opaque 

 tissue, called " bone," differs from the 

 former two in having the intercellular 

 e spaces or meshes filled with phosphate 

 of lime and other earths, instead of a 

 ~ d hyaline or fibrous substance. It may 

 fig. e. -ossifying Carti- be cal i ed pe t r ified tissue— the Quantity 



lage, X 10; a, cartilage r * J 



cells, passing into com- f earthy matter, and therefore the brit- 



pact bone, c, and then , . , 



spongy bone, e. tleness oi the bone, increasing with the 



