88 ANNELIDA. 



6. Dorsal to the alimentary canal is the dorsal blood-vessel, on 

 its ventral side is the ventral blood-vessel, and ventral to the nerve 

 cord the sub-neural vessel. 



7. Find sections of the nephridia. Where are they placed? 

 How do the sections appear? Why? 



Other organs will appear in most of the sections. See if you 

 can identify them. 



Draw an enlarged cross-section. 



Parker and Arkin: The Directive Influence of Light on the Earthworm, 



Allolobophora fcetida. Am. Jour. Physiol., 4, 1901. 

 Sedgewick and Wilson: General Biology. 



AUTOLYTUS CORNUTUS. 



This polychaete lives in cylindrical tubes of its own con- 

 struction that it attaches to seaweeds and hydroids, and is espe- 

 cially interesting because of its method of reproduction, by bud- 

 ding. 



Study live and preserved specimens with the naked eye and 

 with the hand-lens, in order to form a correct idea of its natural 

 color, size, and movements, and then study stained specimens 

 with the low power. 



1. Observe two individuals attached end to end. The ante- 

 rior one is a non-sexual zooid (or original "stock") and is giving 

 rise to a new sexual zooid by budding. Counting the peristomium 

 as one somite, on what somite does the bud begin and what 

 does it represent? 



2. Study the head of the anterior, non-sexual zooid. Find three 

 prostomial tentacles. How are they arranged? Find the eyes. 

 How many pairs are there? Do you find palpsf On the peri- 

 stomium find the two tentacles and a tentacular cirrus. 



3. On the succeeding somites study the parapodia. Observe 

 the large dorsal cirri and the knob-like notopodium with the short 

 unjointed setae. There is no neuropodium. 



4. Identify the pharynx, gizzard, and intestine. 



5. Compare the sexual bud with the non-sexual individual. 

 The adult male and female differ. The outer prostomial tenta- 



