PRACTICAL HISTOLOGY. 



[XII. 



(a.) Observe the collapsed membrane of the fat-cells, with a small 

 oval blue-stained nucleus immediately under the cell-wall. A small 

 quantity of protoplasm surrounding the nucleus may be visible. 



4. Or harden a small piece of the omentum of a rat or other 

 animal in absolute alcohol. Select a piece which contains some fat. 

 Stain it for twenty minutes in lithium-carmine, then place it in acid 

 alcohol (i per cent, hydrochloric acid in 70 per cent, alcohol) ; 

 place it in absolute alcohol ; clear it up with clove-oil or xylol, and 

 mount in Canada balsam. 



(a.) Observe the envelopes of the fat-cells and the nuclei of the 

 fat-cells, the latter stained bright red (fig. 139). Other red-stained 

 nuclei are visible, but they are the nuclei of blood-capillaries between 

 the fat-cells. 



5. Margarine Crystals (H). Place a small piece of fat for forty- 

 eight hours in glycerine. Tease a piece in Farrant's solution. 



(a.^ Notice the large cells some of them with granular contents, 



FlO. 139. Empty envoi opes of 

 Fat-Cells. Alcohol and 

 ether. 



PlG. 140. Fat-Cells containing Crystals of 

 Margarine. 



others with a stellate arrangement of needle-shaped crystals of 

 margarine (figs. 137 and 1 40). If the star of crystals really palmitic 

 and stearic acids be broken up, then the needle-shaped crystals are 

 distributed throughout the cell. 



6. Blood- Vessels of Adipose Tissue (L and H). Make a rather 

 thick section of a mass of adipose tissue in which the blood-vessels 

 have been injected. This can be done by injecting the blood-vessels 

 of a rabbit with a carmine-gelatine mass. As the fat is very soft, the 

 best method of obtaining such sections is to saturate the tissue with 

 paraffin and cut it in paraffin. Mount sections not too thin in 

 balsam. A section which has been saturated with paraffin and cut 

 in this substance must have the paraffin removed by soaking in 



