82 NATURE AND LIFE. 



III. 



Thus we are brought back again, after a rather long 

 circuit, to the tissues of Bichat. In fact, it is by the piling 

 together or the interlacing in a thousand cross-ways that 

 these tissues are formed, and they in turn mingle to com- 

 pose organs. The study of the tissues, or histology, is no 

 doubt that portion of anatomy which, by its amazing and 

 priceless revelations, has most strongly attracted contem- 

 porary physicians and physiologists. The number of ana- 

 tomical elements that come together to make up a given 

 portion of tissue, could no more be computed than that of 

 the grains of sand on the sea-shore. When we think that 

 these elements, having the shape of cells, tubes, and fibres, 

 are measured by thousandths of the thousandth part of a 

 metre, it is clear that a shred of skin or muscle, a bit of 

 brain or bone, contains immense quantities of them. How- 

 ever, this question is only one of secondary interest. 

 What it is important to know is, the arrangement of these 

 elements and the order in which they combine to compose 

 the tissue ; in a word, it is the texture of it. Apart from 

 the tissue-products, which result from merely bringing ana- 

 tomical elements of the same kind into contact, all the 

 other tissues present one sort of element called fundamen- 

 tal, because it predominates, and gives the tissue its chief 

 properties, while also it is associated with other sorts, 

 which are called accessory. Tissue-products thus present 

 the simplest degree of texture, and in their normal con- 

 dition contain no vessels. Of this number are the epider- 

 mis or epithelial tissue, the tissue of nails and horns, which 

 are formed wholly of epithelial cells, the crystalline tissue, 

 w T hich is made up of fibres arranged in concentric layers, 

 etc. The other tissues, that is, by far the majority of the 

 whole, present a very complicated texture. Several dis- 

 tinct sorts of anatomical elements are in these associated 

 in definite grouping. The part fulfilled by the tissue is 



