54 THE NECTURUS 



// two specimens are provided, an injected and an un- 

 infected, the study of the vascular system may be post- 

 poned until the work on the body cavity is completed. If 

 only one specimen is provided, then the vascular system 

 must be worked out with the other systems. 



Pull the digestive system to one side and remove it, thus 

 exposing the urogenital system. 



