LABORATORY EXE&CtSES 



411 



dissected readily. A prepared section of an injected lung should be shown 

 under the microscope. 



Page 179. The moving of particles of cork or bits of wood, etc., by 

 cilia may be shown by pithing a frog, cutting away the lower jaw, and 

 then, with the frog on its back, putting such particles on the roof of the 

 mouth. If this be kept moist with 0.6% salt solution, these bits of mate- 

 rial may be slowly but visibly moved backward to the opening of the gullet. 



In pithing a frog the brain is destroyed, and thus consciousness of any 

 pain, while the rest of the body is left entirely uninjured. Hold the frog 

 in one hand, ventral side against the palm ; put the first finger over top of 

 head and hold against middle finger which, with the other two, grasps the 

 body of the frog. With the back side of the blade of a scalpel placed 

 transversely to the skull, find the groove between the skull itself and the 

 first vertebra. Drive the point of the scalpel into this groove and sever 

 the cord ; then thrust a needle forward through the foramen magnum into 

 the brain box and mix up the brain. In this condition the frog may give 

 reflex movements, but these are from the cord alone. If it is desired to 

 do away with these also, pass a long needle or stiff wire backward from the 

 wound through the neural canal of the spine. 



Page 183. Prepared slides of many forms of pathogenic (disease 

 causing) bacteria can be obtained from dealers in same, and will greatly 

 interest a class if shown under highest powers of the microscope. 



CHAPTER XIII 



Page 191. Prepare the piece of apparatus shown in figure below. 

 By the use of rubber bands as shown, demonstrate to the class how the 

 internal and external intercostals raise and lower the ribs, and thus in- 

 crease and decrease the size of the thorax. 



