_'5.v . Iciosonni. a. < thservc the straight alimentary canal, with 

 an opening at each c-nd. Distinguish mouth, -h< >rt muscular pharynx, 

 narrow oesophagus, wide stomach, and narrow intestine, and the 

 ami-. If necessar) stupefy the animal- partly hy placing them 

 for a time in a dish containing a \\eak solution i alxmt ' j saturated i 

 <>f chloretone i u-e a weaker solution if this injures them. I Xotice 

 vlie ciliary movement within the alimentary canal; in what parts is 

 it found: Are there any peristaltic movements? Xotice especially 

 the large glandular cells which make up the walls of the stomach. 

 Are there any separate glands connected with the alimentary canal? 



h. Is there any method of causing an external current in the 

 water for hringing oxygen and carrying away carhon dioxide? Test 

 with India ink. Mow are the currents produced, and where are tluv 

 f. und ? Make a figure of the animal, showing the alimentary canal, 

 and indicating hy arrows the external currents. 



Are there any indications of internal currents. i.e.. of a circula- 

 ti >ry system ? 



c. In Aelosoma we mid definite excretory organs, of a very simple 

 character. Thev c n>ist of small coiled tuhes, which are found in 

 pairs at intervals attached to the hody wall helow the alimentary 

 canal. Study these carefully. Thev can hest he seen when the 

 animal is placed with ventral side up; and in a region where the 

 alimentary canal is not too wide (oesophagus or intestine). 

 Xoiice that one end of the tuhe is open and hears c'lia. which can 

 he seen in lively movement; this end is called the funnel. Are 

 there cilia elsewhere in the tube? The opposite end of the tuhe i- 

 attached t the hody wall, and opens to the outside. The whole 

 organ is a nephridium. Make as complete a drawing of the nephri- 

 dium. on a large scale, as you can and indicate the ciliary m .vement. 

 The nephridium takes up waste siihstances from the rluid ot the 

 hody cavitv. through its walls. These are washed out hy the ciliary 

 .'.ction, a certain amount of fluid which aids the \\ashing out heing 

 introduced into the tuhe through the opening of the tunnel. 



_'5). Dero. a. This is studied particularly for its yery pecu- 

 liar ri spiratory organs. Xotice however the simple alimentary 

 canal, like that of Aelos ( ,ina, hut perhaps -till simpler. ( )li>erve 

 also that there i- a method of producing internal currents, i.e.. a 



circulatory system, with reddish hi 1. I low is this hlood caused to 



m< >ve ? 



h. Arc- there any external current-: ilVtcrmine with India 

 ink. ) ( (hservc that the-e are at the posterior end in this case 

 ( compare with Aelosr ,ma i . Studv carelully the larijc p"-terior 



