BY DR. KLEIN. 59 



interstitial substance. Hence it is evident that the sheath of 

 protoplasm with which nearly the half of each individual 

 bundle is surrounded consists of a series of hollow half-cylin- 

 ders with their ends in apposition. To preserve the prepara- 

 tions above referred to, the fresh tendon should be placed for 

 a very short time in acidulated water, until it begins to swell 

 just perceptibly; it is then to be transferred to half per c-nt. 

 solution of chloride of gold for ten or fifteen minutes, and 

 washed in distilled water till it acquires a rich color, and then 

 to be mounted in glj-cerin. In cross sections through young 

 tendons of the rat or rabbit, in consequence of the anatomical 

 facts already stated, the bundles look as if they were contained 

 in the meshes of a network of protoplasm, with nuclei at the 

 nodes. Such sections may be best prepared from the caudal 

 tendons, or from the T. Achilles treated with gold and then 

 hardened in common alcohol. 



Adenoid Tissue. It remains to describe the so-called 

 adenoid tissue. By this term is understood a dense reticulum 

 of branched cells, the processes of which are short but of great 

 delicacy. The j'ounger the individual, the more the material 

 of which the reticulum is composed possesses the character 

 of protoplasm ; the older, the more homogeneous the processes 

 appear, and the smaller the quantity of protoplasm at the nodes, 

 which correspond .to the bodies of the cells. There are great 

 differences between the several forms of adenoid tissue, which 

 it will be most advantageous to study in connection with the 

 tissues in which they are respectively met with, e. </., lymphatic 

 glands, intestinal mucosa, etc. The best objects for study are 

 the mesenteric glands or the thymus of the calf, and the h*m- 

 phatic follicle of the intestine of the rabbit. These must be 

 hardened in Mailer's fluid or in diluted alcohol. As soon as 

 the tissue has become firm enough, thin sections are prepared, 

 which are agitated with water in a test tube, until they present 

 the appearance of a reticular membrane. They arc then covered 

 in glycerin, with or without previous staining. For more 

 minute descriptions, see Chapter VI. 



Development of Connective Tissue. Fibrous connec- 

 tive tissue is ikMap&d-froin .culls in two ways, as follows: 



At a certain stage of embryonal life, those organs which, at 

 birth and in the adult consist of fibrous tissue, are composed 

 exclusively of embryonal cells. As development proceeds, 

 these cells, which are originally roundish, are either transformed 

 into a network of branched cells, or lengthened out, so as to 

 form bundles of spindle-shaped cells. At first both the bodies 

 and processes of the cells, whether branched or spindle-shaped, 

 consist of granulous protoplasm. The protoplasm subse- 

 quently undergoes a process of splitting, by which it is trans- 

 formed into fibrils. This change commences in the processes, 



