78 PRACTICAL HISTOLOGY [x 



the other half, after staining it for an hour in 

 picrocarmine. Observe that the fat-cells are stained 

 a deep brown-black (cp. Lesson ix. 4, 6). If the tissue 

 before being mounted be kept in alcohol (e.g. 70 p.c.) 

 for a day the tint of the fat globules will become deep 

 black. 



18. Make a moist film preparation of the sub-cutaneous 

 connective tissue of a rat containing a small amount of fat, and 

 fix it in alcohol. Stain with haematoxylin and eosin. Examine 

 (h.p.) ; the fat-cells will probably show a distinct sponge- work or 

 network of cell substance. 



DEMONSTRATIONS. 



1. Transverse section of ligamentum nuchse. Note 

 the commonly angular outline of the elastic fibres, and 

 the small amount of white fibrous tissue. 



2. Section of a lobule of fat (Miiller's fluid, hsema- 

 toxylin, turpentine or xylol, balsam). Note the closely 

 set groups of cells, the small amount of cell substance 

 at the periphery of each cell, and the flattened nucleus. 



3. Section of umbilical cord to show mucous con- 

 nective tissue (formaline, picrocarmine). Note the 

 large amount of homogeneous substance, the scanty 

 fibres, and the branched cells. 



NOTES. 



Hardening tendon. A tendon may be hardened by placing it 

 fresh in 30 p.c. alcohol for a few hours, and then in 75 p.c. 

 alcohol ; or by placing it in a saturated aqueous solution of 

 corrosive sublimate for a day. 



