mi: 010 



gliif-produci: tissue; they are sharply 



ditl'erentiatrd 1'it'iii ili- 'iMiding.s, and become adn 



in coiiM- [luMic* nf their p.-culiar i properties, to the as- 



sumption >f >pecial functions. Cartilage serves in part to keep 



;'s open (cartilag' tree). in 



for the protection of vital OKL' a; in a firm 



ilajjinoiisciai.il::;. . .f th' lahvrint h. vertebral 



i for the support of structures projecting from 



the Mil-face of the body .imhs, branchial rays, etc.). 



mi"- tin!' ::'"rd firm p"ints of attachment for 



masses of muscle. imbedded in tin- neighboring parts 



of tin* muscles entering into linn union with them. In thi> ma 

 there 1ms ari-M-n through hi rphoeis a different: 



;al apparatus, whi.-h increases in coin! in the same 



proporiioii as it acquires more manifold rela- ii tlu in 



latuiv. 



Cartilaginous and conn. ues, finally, are capable of a 



further histological metamorphosis, since the last form of sustenta- 

 tive -ul-tnneo, osseous tissue, is developed from them in conne 

 with the secretion of salts of lime. There are there/ore bones 



>m a cartilaginous viatrix and others from one of con- 

 nective tissue. With the appearance of bone, the skeletal apparatus 

 of Vertebrates has reached its highest perfection. 



Even if the mesenchymo has by these processes experienced an 



.ordinarily high degree of dilV. i i a great dive: 



of form, the histological processes of differentiation which take place 

 in it arw iifverthel. ss not yet exhausted In the gelatinous or 

 connective-tissue matrix canals and spaces arise in which blood and 

 lymph move in accomplishing thir function of intermediating in 

 the metastasis of the organism, not only conveying the 

 thuds to the individual organs, but also conducting away both the 

 Bubetanoefl which owing to the chemical processes in the tissues 



have become useless and the superfluous thuds. Out of these 

 first beginnings arises a very compl _ranic apparatus. The 

 larger cavities constitute a and acquire peculiarly 



ructed thick walls, provided with non-striate muscle 

 and elastic fibres, in which three ditTerent layers can be dis- 

 tinguished as tunica intiina. media. ' ia. A small part 



of the blood-passages, especial! 1 \ y an abundance of 



muscle-cells, is converted into a propuLdve apparatus for the fluid 



the heart. The elementary corpuscles that circulate in the 



