CILIARY MOTION. H5 



LESSON XXVI. 



PITHING CILIARY MOTION NERVE- 

 MUSCLE PREPARATION- 

 NORMAL SALINE. 



1. To Pith a Frog. Wrap the body, fore and hind legs, in a 

 towel, leaving the head projecting. Grasp the towel enclosing 

 the frog with the little, ring, and middle fingers and thumb of the 

 left hand, leaving the index finger free. With the index finger 

 bend down the frog's head over the inner surface of the second 

 finger until the skin over the back of the neck is put on the 

 stretch. With the nail of the right index finger feel for a 

 depression where the occiput joins the atlas, marking the position 

 of the occipito-atlantoid membrane. With a sharp, narrow knife 

 held in the right hand, divide the skin, membrane, and the 

 medulla oblongata. Withdraw the knife, thrust a " seeker " into 

 the brain cavity through the opening just made, and destroy the 

 brain, To prevent oozing of blood, a piece of a wooden match may 

 be thrust into the brain cavity. If it is desired, destroy also the 

 spinal cord with the seeker or a wire. The knife used must not 

 have too broad a blade, else two large blood-vessels will be 

 injured. The operation should be performed without losing any 

 blood. 



2. Ciliary Motion. 



(a.) Pith a frog, destroying the brain and the spinal cord. 

 Place the frog on its back. Divide the lower jaw longitudi- 

 nally, and carry the incision backwards through the pharynx 

 and oesophagus. Pin back the flaps. Moisten the mucous 

 membrane, if necessary, with normal saline. 



(b.) Make a small cork flag, and rest it on the mucous 

 membrane covering the hard palate between the eyes. It 

 will be rapidly carried backwards by ciliary motion towards 

 the stomach. Repeat the experiment, and determine the 

 time the flag takes to travel a given distance. 



(c.) Grains of charcoal or Berlin blue are carried back- 

 wards in a similar manner. 



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