.ABORATORY PRACTICUM. 



PROTOZOA. 



I. Protoplasta. (" Rhizopods " in restricted sense.) 



These are niinnte globnles of protoplasm, i. e. "cells'" without cell wall. 

 Some are naked, others protected by a shell. Occur in enormous (juantities in 

 slime at bottom of jionds and in swamps, particularly in the moisture col- 

 lected upon bog-moss (Sphagnum). 



I , Squeeze out a drop of water from a txift of Sphagnum : let it fall in 

 the center of a clean slide : cover and examine 100''. cf. Leidj% Plates. Study 

 several drops in this way and identify. If a form is interesting, bring it to 

 the center of the field and adjust higher power 300-600''. 



2. Collect a few slimy leaves and sticks from a stagnant pond or ditch. 

 Place in a shallow dish with water from the same place. [This is best trans- 

 ported in a closed can.] Put a drop of this water upon a slide, mix with it 

 the scrapings from a slimy leaf, cover and examine as above. {Continue the 

 above iuvestigafions [1 a^id 2] until yon have identified three of the fothnc- 

 ing forms : — Amoeba, Difflugia, Euglypha, Nebela, Arcella, Hyalosphenia, 

 Qnadnda, Cyphoderia. Make a draiving of each of the three forms, noting 

 the strnetnre and the character of the shell tvhen present .) 



3. Study of living forms. Life is indicated by the movement of the 

 protoplasm. Amoebae will always be foiind alive, as so minute a drop of 

 dead protoplasm woiild disintegrate at once. On the other hand, the shells 

 of the other forms are very enduring and are often empty. In such shells a 

 deceptive appearance of life may be caused by swarms of minute infusoria, 

 etc. , which sometimes inhabit them. 



3, "• If the form is an Amoeba, draw several successive shapes. Note 

 the granular endoplasm and clear ectoplasm. Are the pseudopodia pointed or 

 blunt V [cf. Leidy for different species.] Study the particles of food. What 



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