HISTOLOGICAL DEMONSTRATIONS. 91 



are placed in gold chloride solution, and treated as directed 

 in 330. The nucleus of the fibre is stained. 



d. The nuclei of the fibres may also be well stained 

 with picro-carmine. A piece of frog's bladder when treated 

 with this dye (322) gives beautiful preparations. 



137. Structure of Non-striped Muscle. Strip off a 

 small piece of the muscular coat of the intestine, hardened 

 in dilute nitric acid as above described. Tease it with 

 needles in a drop of Farrants' solution; cover, and examine. 



Each fibre is a spindle consisting of a nucleated band 

 of sarcous substance, without an envelope. The whole 

 fibre is evidently an elongated cell, the protoplasm of which 

 has been transformed into a substance, that like the sub- 

 stance of a cilium contracts in a definite direction. 



138. Examine a preparation of frog's bladder, carmin- 

 ised. Notice the spindle-shaped and the triradiate fibres. 

 The latter might, by the inexperienced observer, be mistaken 



for nerve cells. 



Excellent preparations of the fasciculi of non-striped 

 muscle, divided transversely and longitudinally, will be 

 found in the sections of stomach and intestine at a future 

 time. 



139. Striped Muscle. The Sarcolemma (H). a. 

 Decapitate a frog, and isolate one of its muscles ; the 

 sartorius is to be preferred, because its fibres are parallel 

 and easily separated. Make a vertical section of the muscle 

 with scissors, and tease the fibres in a drop of water, in 

 order to study the sarcolemma. Look for the sarcolemma 

 raised from the sarcous substance, by imbibition, in the form 

 of a vesicle, or stretched between the ends of fibres broken 

 across, or prolonged as a funnel-shaped process from the 

 end of a ruptured fibre. 



b. Effect of acetic acid. Remove the preparation from 

 under the lens, raise the cover and add a drop of dilute 

 acetic acid. It renders the sarcous substance very trans- 

 parent, and reveals the nuclei of the sarcolemma. In 

 mammals the nuclei are only found under the sarcolemma. 

 In the frog's muscle they are also found amidst the sarcous 

 substance. 



