ANIMAL ORGANIZATION. 105 



for carrying on the functions of life. Textures 

 of greater strength than can be constructed by 

 membranes alone become necessary for the 

 security, the support, and the defence of im- 

 portant organs ; and more especially for the 

 execution of extensive movements. For ob- 

 taining these advantages a peculiar species of 

 fibres is provided, formed of a much denser 

 substance than even the most consolidated 

 forms of cellular texture. The animal product 

 termed albumen possesses a much stronger 

 cohesive power than gelatin^ which is the basis 

 of membrane. The addition of albumen, there- 

 fore, procures the quality required : and the 

 fibres that are produced by its combination 

 with gelatin are opaque, and of a glistening- 

 white colour. By interlacing fibres thus com- 

 posed, a close texture is formed, which is ex- 

 ceedingly tough and unyielding. These fibrous 

 textures, as they are termed, while they retain 

 the flexibility of membranes, greatly surpass 

 them in strength ; but, being at the same time 

 incapable of extension, they are necessarily de- 

 void of elasticity. Hence they are adapted to 

 form external tunics for the investment of such 

 organs as are not intended to vary in their size. 

 Occasionally these fihrous capsules, as they are 

 called, send down processes into the interior of 

 those organs, for the purpose of giving them 

 mechanical support. This is the case, for in- 



