36 THE SIMPLE TISSUES. 



Retiform or adenoid tissue, S. of a Lymph Gland of 

 an ox or sheep. 



Injected interstitially with a 0*25 P- C - sol. AgN0 8 , hardened in 

 alcohol, cut by freezing in gum, and stained with Hsematoxyline, 

 m. B. 



(L) Find the lymph sinus in the outer part of the section, 

 (//) recognise the delicate branching tissue extending across 

 the spaces, on this find endothelial outlines and the nuclei 

 belonging to the cells. The supporting material is connective 

 tissue (gelatigerious tissue). Numerous cells, the lymph cor- 

 puscles, are distributed throughout the meshes of the branching 

 material, very closely crowded in the follicular tissue outside 

 the sinuses. These cells are identical with the white corpuscles 

 of the blood and originate from the r.pitheliod elements upon 

 the branching tissue. 



Take a section of the fresh gland, cut by freezing, shake it vigorously 

 in normal saline in a test- tube for a few minutes. Mount the fragmerits 

 in Farrant's Solution, tinged with Picrocarmine. The retiform tissue,, 

 now cleared of the corpuscles, will show its finer branchings. 



g Fatty Tissue. Epiglottis of kitten or young human skin. 

 V.S. (p. 3, s. 22 & 24, c. P.,>. B.) (L) Find fat cells stained 

 black by the osmic acid. (//) Trace the accumulation of fat in 

 the cells, first as small granules in the peripheral cells, growing to 

 mulberry-like masses in others, and ultimately to a single large 

 globule which distends the cell uniformly. Fatty tissue will 

 be of common occurrence in the tissues and organs studied in 

 tlie sequence. 



After treatment with essential oils for the purpose of embedding in 

 paraffin the cell envelopes are usually found empty, their contents having 

 boen removed by the solvent. Fatty tissue mounted in glycerine exhibits 

 crystals of trimargarine and tristearine, triolein only remaining fluid 

 at ordinary temperatures. 



