PART I.-MORPHOLOGY. 



INTRODUCTION. 



The following course of elementary zoology has been designed in order to give the 

 student a general idea of the principles of the science, rather than a comprehensive survey 

 of the whole animal kingdom. In a short course of this nature it is impossible to study 

 in detail examples of every group, and therefore those types have been selected with 

 which it is most important that the student should become acquainted. 



In order to derive full advantage from the course, the following elementary rules of 

 laboratory procedure must be observed. 



Use of Microscope. Always see that the eye-piece and objectives are clean. 

 Lenses can usually be cleaned by breathing on them and then wiping with a clean cloth, 

 preferably of silk. If any balsam has got on to the objective, the attention of the demon- 

 strator should be called to it. 



When examining an object always use the low power first. When focussing with the 

 high power use the fine adjustment only and be very careful to avoid touching the cover- 

 glass with the objective. 



Use the plane mirror with the low power and the concave with the high. 



Microscopic Preparations. Always clean slides and cover-glasses before use. 

 When covering an object, hold the cover-glass by the edges in order to avoid leaving finger- 

 marks on it. Lower it gently on to the drop of liquid to avoid the inclusion of air-bubbles. 

 Be very careful not to use too much liquid for mounting objects, as in this case it will 

 run on to the top of the cover-glass and obscure vision. If this happens make a new 

 preparation. 



Dissecting. Whenever possible dissect under water, as this prevents delicate objects 

 from drying up and becoming distorted ; in addition the various organs are supported 

 and seen to better advantage. Change the water whenever it becomes turbid. 



When exposing vessels and nerves dissect along and not across them, and keep the 

 tissues slightly stretched. 



Keep your instruments sharp, and always clean and dry them after use. 



Drawing. Make your drawings in the spaces provided .for them. Do not make 

 rough drawings on other paper and later on transfer them into this book ; above all only 

 draw what you see, not what you imagine to be present, and do not make copies of 

 diagrams from text-books. Always use a sharp pencil. Label every structure shown 

 in your drawings and insert the scales to which they are made. 



