INTRODUCTION 21 



Give each preparation careful study before starting a draw- 

 ing. 



The directions for laboratory study are merely suggestions 

 with regard to methods and order of work; the specimen is 

 the thing being studied. Do not be afraid to do some things, 

 or to make some drawings not asked for in the outlines, if 

 you can thereby get a clearer idea of the structure or add 

 further to your knowledge of the animal. Most of the 

 questions asked in the outlines can be answered from the 

 specimen if the search is made, but if help is necessary call 

 upon the instructor for aid. 



Always give a clear and definite title to each drawing, 

 indicating what aspect of the specimen is shown; also clearly 

 name the parts shown in the drawing. Write labels parallel 

 to the bottom of the page and connect to the part desired by 

 faint continuous lines (these are better than dotted lines). 

 The title of the drawing should be followed by an indication 

 of the scale of the drawing, e. g. x | means one-half the 

 natural size, x 5 means five times natural size. 



Dissection 



The object of dissection is to separate the various organs 

 or parts in such a way as to show their form and relation 

 to each other. It consists largely in removing the con- 

 nective tissue which holds the parts together. 



Fix the specimen firmly in a position that will be con- 

 venient for work, usually with the head away from you. 

 If pins are used stick them obliquely into the wax of the 

 dissecting pan. Large specimens should be moistened from 

 time to time to keep from drying, and small animals should 

 be dissected under water. 



Before starting a dissection study the specimen care- 



