APPENDIX. 



There are some fundamental truths in the science of physiology which 

 the student best appreciates when he sees the actual experiments from 

 which they are deduced. There can be no doubt that actual laboratory 

 work for each student is the ideal to strive for in the teaching of physi- 

 ology, but limited time allotted to the subject and the expense which 

 such a laboratory incurs prohibit the general adoption of the method 

 in most dental schools. The authors have found the following experi- 

 ments to be of value in their dental classes, since they increase the in- 

 terest of the student in the more important facts of the circulation, 

 respiration, and secretion. They are given as demonstrations before 

 small sections of the class. 



The following outlines are not intended to give complete directions 

 for the experiments, but to explain the various steps of the experiments 

 to the individual students. Full laboratory directions for all the experi- 

 ments are found in Professor G. N. Stewart's Manual of Physiology 

 (Longmans, Green, & Co., 1914). 



DEMONSTRATION No. 1. 



A. The Circulation of Blood in the Vessels of the Tadpole's Tail. 



A tadpole, whose brain has been destroyed by a needle is laid on a 

 glass slide and a large cover-glass is placed over the tail, which is then 

 examined by the low power lens of a microscope. The general charac- 

 ters of the flow of blood through the vessels can be seen (p. 179). 



B. The Nature of the Cardiac Contraction. 



The brain of a turtle is destroyed by a sharp blow on the head. The 

 ventral portion of the carapace is removed by a saw cut along each side 

 and by dissecting it from the tissues, care being taken to avoid haemor- 

 rhage. The heart, beating inside the pericardial sac, is seen posterior 

 and dorsal to the pectoral arch. By tying the fore-limbs firmly above 

 the head, the pectoral girdle is pulled apart and more space is obtained 

 for the observation of the heart. The pericardial sac is incised and the 

 auricles and ventricle exposed. The auricles appear as two thin-walled 

 sacs above and to each side of the ventricle. If the tip of the ventricle 

 be raised the sinus venosus is brought into view. It receives the supe- 

 rior and inferior vena cava, and joins the right auricle. 



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