CONNECTIVE TISSUE. 29 



mucous tissue as above described. The cells are larger and the meshwork wider in the part 

 farthest from the vessels. The intercellular substance, even at this age, contains connec- 

 tive-tissue fibres, and their number increases in older specimens ; hence the necessity for having 

 as young a foetus as possible to see the uncomplicated characters of this tissue. {Indicate these 

 corpuscles in PI. V., Fig. 6.) 



If a similar preparation be teased with needles and stained with methyl-aniline before 

 it is mounted, it is easy to isolate flattened endothelial plates with wing-like expansions. 



ADENOID TISSUE. 



This tissue forms the basis of the lymphatic glands and the spleen, and occurs widely 

 distributed as simple lymphatic glands or in diffuse patches in many organs oi the body. It 

 was formerly believed to consist of branched corpuscles, whose processes anastomosed with 

 the processes of adjoining cells, so as to form a network, which was filled with lymph-cor- 

 puscles. We now know, however, that it is built on the same type as connective tissue. It 

 consists of a ground substance, dense reticulum or network adenoid reticulum made up of 

 excessively fine homogeneous fibrils and membranes, which form a honeycomb-like open 

 network. Transparent, flattened connective tissue or endothelial cells with oval flattened 

 nuclei are applied here and there to these fibres, and partially embrace or enclose them just 

 as in connective tissue. The large nuclei which usually occur at the nodes of the network, 

 and which were formerly regarded as the nuclei of the branched cells, are really the nuclei of 

 the flattened cells applied to the fibres. This meshwork is filled with lymph-corpuscles. 

 These are small cells exactly like colourless blood-corpuscles, with a small round nucleus, 

 which is thus easily distinguished from the large oval nucleus of the endothelial plate. They 

 are- not all, however, of the same size At first sight only these lymph-corpuscles are seen, 

 and so densely packed are they that one requires to shake or pencil them out of the mesh- 

 work before the adenoid reticulum can be brought into view. 



PREPAKATION (a). Place a small piece of a fresh lymphatic gland of an ox, or an entire 

 gland from the abdominal cavity of a cat, dog, or rabbit, for a week in Miiller's fluid. Make 

 transverse sections. Stain a section deeply with logwood, and then place it in a test-tube 

 with water and shake it briskly for five minutes or so. This detaches the lymph-corpuscles, 

 and the previous staining enables one to see the section. Float it on to a slide, and mount in 

 Farrant's solution. 



(3) Nitrate of Silver Injection and Logwood. Into a fresh mesenteric or lymphatic gland, 

 thrust the nozzle of a hypodermic syringe filled with a quarter per cent, silver nitrate solution, 

 and push in the silver solution into the gland so as to form an artificial oedema. The gland 

 must be tinged with the silver solution. Place it for twenty-four hours in alcohol and then 

 make sections by freezing. At first the sections will be colourless ; but on exposure to light, 

 wherever the silver has penetrated, they will be stained brown. Stain a section in logwood, 

 and mount it in Farrant's solution or dammar. See also lymphatic gland (p. 77). 



EXAMINATION (L). Indistinct indications of the adenoid reticulum here and there 

 crowded with lymph-corpuscles stained blue will be seen. Select a spot where few corpuscles 

 are to be seen and examine it with (H). Study the excessively delicate adenoid reticulum, 

 with here and there a large oval nucleus lying on it, especially near a node. These are the 



