XII] CILIATED CELLS. MUSCLE CELLS 95 



Note the plexus of unstriated muscle cells 1 . 



4. a. Tease out in dilute alcohol a little of the 

 body muscle of a worm (the worm is cut up, washed in 

 30 p.c. alcohol and kept in fresh 30 p.c. alcohol for one 

 to three days). Note (h. p.) the cells are longer and 

 much flatter than in the frog, when seen flat they show 

 a more or less distinct longitudinal fibrillation. 



b. Stain a small piece with acid hsematoxylin, 

 wash, and tease in dilute glycerine. The nuclei are 

 round or oval, and are on the surface of the cells; 

 some will probably have been removed in teasing. 

 (The position of the nucleus varies in different inverte- 

 brate muscle cells.) Compare with the muscle cells of 

 vertebrates, 2. 



5. Treat, as in 4 a, a Jittle of the yellowish anterior part 

 of the posterior adductor muscle of an anodon. Note (h. p.) the 

 double oblique fibrillation of the muscle cells ; the angle between 

 the two sets of markings is greater the more contracted the cell. 



6. Cardiac muscle. Treat a small piece of the 

 ventricle of just killed rat or mouse with 35 p.c. potas- 

 sium hydrate by the method given in 2. In the 

 teased specimen, note 



The isolated muscle cells; they are short, thin 

 columnar cells, many having a short process coming off 

 obliquely from the body of the cell. At about the 

 centre of each cell is a nucleus. The transverse stria- 

 tion is not very distinct. The cells have no sarcolemma. 



7. Isolate the cardiac muscle cells of the frog by the method 

 given in 2. 



1 A fine plexus may also be seen in the mesentery of the newt. 



