4(> PHYSIOLOGICAL SERIES. 



B. 



FLEXIBLE BONDS OF UNION AND SUPPORT- 

 VERTEBRAL COLUMN- JOINTS. 



FLEXIBLE BONDS OF UNION AND SUPPORT. 

 AREOLAR TISSUE. 



B. 1. Small portion of skin and subjacent structures of a Calf 

 ( Bos taunts), showing the areolar tissue that unites them. 

 It consists mainly of delicate wavy bundles of tough, flexible, 

 inextensile and inelastic white fibrous tissue, loosely inter- 

 laced so as to allow of motion in any direction. The return 

 to the position of rest ia effected by fine branched fibres 

 of yellow elastic tissue. 



Above is a piece of separate areolar tissue. 



SPECIAL ELASTIC STRUCTURES. 



Loisel, Jour, de 1'Anat. et Physio!., t. xxxiii. 1897, 

 p. 129. 



Not essentially connected with the Skeleton. 



B. 2. Portions of three specimens of Scallop (Pecten maximus), 

 showing the two ligaments by which the valves are attached 

 to one another. The external ligament is structureless and 

 inelastic ; it extends along the straight hinge-line, but is 

 interrupted near its middle by the internal ligament. The 

 internal ligament is a wedge-shaped black mass, lodged in 

 a depression of the shell; it grows by additions to its ventral 

 border; being very elastic, and compressed when the adductor 

 muscle contracts, it acts like a spring, keeping the valve 

 apart in the most constant feeding-position of the animal, 

 and also acts as an opponent of the muscle by which 

 swimming is effected. 



Quekett, Trans. Micro. Soc., vol. ii. 1849, p. 1. 



B. 3. A portion of the elastic ligamentous substance from the 

 belly of an Elephant (Eleplias indicus). 0. C. 74. 



" On the abdomen of most quadrupeds are to be found elastic 

 ligaments, especially on that of the elephant, which is a constant 



