VORTIGELLA. 35 



3. Of the animal as a whole. 



(a) Method of contraction of stalk and of 



disk. 



(b) Mode of extension of contracted animal. 

 Make a diagram of an expanded and of a con- 

 tracted animal and label corresponding parts. 



Make diagrams of stalk (a) in extended state ; 



(b) when contracted. 

 IV. Reproduction. 

 Search for : 



1. Specimens dividing by fission. 



2. Motile forms. When found study with D 2. 



Observe the secondary band of cilia. Look 

 for the contractile vacuole. 



3. Conjugation : the union of a small motile 



individual with a larger sedentary form. 

 Y. Chemical Experiment. 



1. Stain with iodine ; record the result. 



