70 ZOOLOGY DIRECTIONS 



correspond externally? Hold the worm in your left hand and 

 with a dissecting needle note that these septa break away fairly 

 readily. With the needle pressing outward from the cut against 

 the body wall run it along the body until the septa have been 

 broken along both sides of the body. Now with pins open the 

 body wall out flat against the wax in the bottom of a dissecting 

 pan, allowing the heads of the pins to point away from the body 

 of the worm at a broad angle so as to be out of the way during 

 later dissection and examination. 



Before beginning the study of individual organ systems, 

 examine the opened specimen and locate the following land 

 marks. At the anterior extremity of the body is the pharynx, 

 the anteriormost part of the digestive tract. Posterior to this 

 are several large white objects, the sperm sacs, which hide the 

 digestive tract in this region. Behind the sperm sacs the large 

 cylindrical tube which continues through the length of the body 

 is the digestive tract the parts of which will be studied in detail. 



In all of this work remember that the septa may be 

 crowded either forward or backward by some of the organs. 

 For this reason it is necessary to observe in what cavities the 

 organs lie, rather than observe the external body markings of 

 segments in the region occupied by the organs. If a structure oc- 

 cupies more than one segment, the places where the septa crossed 

 it are fairly easily recognized. 



REPRODUCTIVE SYSTEM 



In studying this system be careful to prevent injury to the 

 organs of other systems. 



A. Male Reproductive Organs 



1. Three pairs of sper)n sacs, large white sacs at sides of 

 and above esophagus. Some of them may not be very large be- 

 cause the specimens were not at the height of sexual activity 



