PRACTICAL HISTOLOGY. 



[XV. 



nised by the dilatations in their course, and by the character of the 

 endothelial cells lining them. By focussing deeply, the silver lines 

 of the endothelium of the serous membrane may be seen. 



6. Methylene-Blue Method (S. Mayer). Into the blood-vessels 

 of a cat e.g., from the aorta inject the following solution : 



Methylene-blue (S. Mayer's) 1 i gram. 



Normal saline ....... 300 cc. 



After an hour or so, open the abdomen ; the intestines appear 

 blue ; cut out a portion of the muscular coat and place it in the 

 following mixture : 



Picro-Grlycerine Mixture. 



IOO CC. 

 100 ,, 



Saturated watery solution ammonium picrate 

 Glycerine ...... 



On teasing a small piece of the muscular coat in the same mixture, 

 isolated muscle cells are readily found, the nucleus being stained of 

 a faint rosy-pink. 



ADDITIONAL EXERCISES. 



7. FibriUar Plexus in Muscle-Cells (H). Kill a newt, open its abdomen, 

 and pin out its intestine and mesentery on a thin piece of cork with a hole in 

 it corresponding to the mesentery. Place it for 

 twenty-four hours in a 5 per cent, solution of am- 

 monium chromate. After this wash away all the 

 chromate, stain a piece of the mesentery in logwood, 

 and mount it in balsam. 



(a.) In the membrane observe narrow strands of 

 non-striped muscle composed of very large fusiform 

 cells. In the large nuclei a plexus of fibrils, while a 

 leash of line fibrils will be seen in the perinucloar part 

 stretching from the poles of the nucleus to the ends of 

 the fibre. 



8. Fibrils in Smooth Muscle. These may be seen 

 for a short time by macerating small pieces of the. 

 stomach of a frog for twenty-four hours in dilute 

 alcohol, or in 8-10 per cent, of sodic chloride (Enyel- 

 mann).' 2 



9. Isolated Smooth Muscle-Cells. To get these 

 cells quickly macerate a small piece of the muscular 

 coat of the stomach, intestine, or bladder in 33 per 

 cent, caustic potash for 15-20 mins. Tease and 

 observe in the same solution. Water must not be 



added, else the effect of weak caustic alkalies is produced, viz., solution of 

 the cells. 



1 To be obtained from Dr. Grubler, Leipzig, or Bindscheidler & Busch, 

 Basel. ' 2 Pfliiger's Arch., xxv. 



FlQ. 1 66. T.S. Smooth 

 Muscle of a Cat's Intes- 

 tine. Chromo - acetp - 

 osmic acid. Shows in- 

 tercellular bridges, and 

 at a an artificial slit, 

 X 1000. 



