92 GENERAL ' BIOLOG Y 



HI. Microscopic Anatomy. (Histology.) 



On the slides furnished are sections across the body in the 

 region of the stomach-intestine, and these are stained in 

 drder that the various tissues may be more plainly seen. 



1. Study the entire section and identify the following 

 structures: (a) body wall and its layers; (6) ccelom; (c) 

 intestine; (d) dorsal and ventral bloodvessels; (e) nerve 

 cord. Other organs likely to be found are setse, excretory 

 organs, septa. 



Make a drawing of the entire section showing all the 

 parts mentioned, but not attempting to indicate the cells 

 which make up the tissues. 



2. Body Wall. With the high power study the body wall 

 and make out the cuticle, epidermis, circular muscles, longi- 

 tudinal muscles, and a delicate layer of cells lining the ccelomic 

 cavity, the peritoneum. Make out the cellular character 

 of the various layers and make a drawing of a small segment 

 of the body wall showing the layers and the cells which 

 compose them. 



3. Intestine. Are the walls of the same thickness through- 

 out? The dorsal infolding of the intestinal wall is called 

 the typhlosole. How much of the cavity of the intestine 

 does it occupy? Make a careful study of the tissues and 

 cells of the intestinal wall; from without inward these are 

 as follows: Chlorogogue, pear-shaped cells rather loosely 

 arranged; between the bases of the chlorogogue cells are 

 small scattered fibers, the longitudinal muscle; a definite 

 and clearly marked circular muscle layer; inside of this there 

 may be spaces, the bloodvessels of the intestine; lining the 

 intestine is a thick layer of ciliated, columnar epithelium. 



Draw a portion of the wall as seen with the high power, 

 showing the cells of each layer. 



