YELLOW ELASTIC TISSUE. 115 



difficulty is experienced in detecting the bioplasm of 

 this tissue, if it is prepared according to the plan I 

 have described. The carmine fluid tinges the bioplasm 

 of this tissue as well as every other kind ; and in 

 properly prepared specimens oval masses of bioplasm 

 are seen adhering to the fibres of yellow elastic tissue, 

 and bear to it the same relation that the bioplasm of 

 some other tissues bear to the formed material of 

 these. The bioplasm of yellow elastic tissue is so 

 easily demonstrated in the young ligamentum nucha3 

 of the lamb, in which the oval masses may be seen so 

 distinctly and in such great numbers, that one can- 

 not but feel astonished that any doubt should 

 exist on the point. But in such questions conjec- 

 tures and speculations have hitherto influenced both 

 teachers and pupils more than accurate observation. 

 By careful examination fibres may be found in 

 various stages of development, from the thinnest and 

 scarcely visible line to the well-known distinct cylin- 

 drical fibre. The bioplasm is seen as an oval mass 

 upon one side of the fibre, and passing from either 

 extremity to the surface of the fibre may be detected, 

 with the aid of high powers, an extremely delicate 

 tissue, which is the soft and imperfectly formed yellow 

 elastic ligament. In the case of some of the larger 

 fibres, I have been able to trace a gradual alteration 

 in density of the delicate tissue just referred to, in 

 proceeding from the mass of bioplasm towards the 

 fibre until the firm dense texture of the actual yellow 

 elastic tissue is reached. The new tissue thus pro- 

 duced contributes to the thickening of the fibre. The 

 appearance seen in many cases is such as to justify 

 the inference that the bioplasm moves along the sur- 

 face of the fibre, leaving behind it as it goes a small 

 proportion of soft formed, material, which gradually 

 undergoes condensation, and becomes slowly con- 

 verted into yellow elastic tissue. In this way each 

 fibre is increased in thickness. Concerning the 



i 2 



