STARFISH 109 



e. The respiratory tree. — Position ? Shape 1 At- 

 tachments ? 

 Draw the digestive system alone. 



B. — The Reproductive System. 



At base of ray find the sexual glands, the ovaries 

 pinkish, and the testes yellowish-white. 



a. The reproductive organs. — How many in each ray ? 

 Do you find both ovaries and testes in the same 

 animal ? Compare them as regards arrangement, 

 shape, size, color, structure, etc., with the hepatic 

 cceca. Where do they open? If possible, com- 

 pare specimens collected in summer with others 

 taken in the spring or autumn, and note the ex- 

 treme differences in the size and color of these 

 organs. 

 Draw the reproductive system in an outlined body. 



C. — The Waier-^asGular System. 



If obtainable, examine specimens in which the water- 

 vascular system has been injected. Injected specimens 

 may be prepared as directed. The madreporic body, am- 

 bulacral feet, and the radial water-tubes, all of which 

 form part of the system, have previously been examined. 



On each side of the vertebral ridge find 



a. The ampullae or water-sacs. — "What is their exact 

 position in the ray ? Shape ? Size ? Structure ? 

 Tear one open and note that it is hollow. Is its 

 wall distensible? Lay a slender pencil in the 

 ambulacral groove, so as to compress the ambu- 

 lacral feet, and notice the efl'ect upon the am- 

 puUse. Is there communication between the am- 

 pullae and the feet ? How does the number of 



