PROTOPLASM AND SIMPLE ANIMAL FUNCTIONS 461 



liquids when exposed to the air and light. Observe the minuteness of 

 these vegetal cells; their vast multitude and their spontaneous movements. 



For knowledge of the bacteria see the text-books on bacteriology. 



Expt. 3. The third slide contains the important protozoan rhizopod 

 Ameba proteus. (See Chapter I.) Use a low-power (two-inch) objective 

 to find one of these, the simplest of living animals. Note its transparency,its 

 extreme simplicity, the nucleus, the metaplasm, and the vacuoles. Watch 

 its slow creeping along the slide and their quite characteristic and unique 

 use of protoplasmic streaming into pseudopodia for locomotion, and for 

 surrounding food-particles. Observe how it tends to contract in area 

 on being stimulated and that it gradually extends numerous pseudo- 

 podia again when allowed to rest. No cell-wall can be discovered. 

 Observe food-prehension and vacuole-bursting. 



Make drawings of as many shapes of one ameba, in definite successive 

 periods, as possible. If necessary, use the warm-stage. 



This observation of Ameba (because the type of relatively independent 

 undifferentiated protoplasm) is one of the most important experiments 

 possible in class-work in physiology. Here is the very essence of spon- 

 taneous vital activity. Do not miss obtaining much from it in the hours 

 allotted to it. See text-books of biology for details. 



Expt. 4. The fourth allotment on the slide contains one or more 

 species of the ciliated infusorium Paramecium. Use first the No. 3 

 objective and observe this unicell's mode of poking about among the 

 vegetal and mineral debris in search of food, much as fishes do. Note 

 its various movements, backward and forward with almost equal 

 facility; its mode of turning shows well the fluidity of the protoplasm. A 

 large paramecium is said to weigh about 0.00017 mgr. and to be capable 

 of raising 0.00158 mgr. 



Now adjust the No. 5 objective and kill the animals by gentle heat or 

 poison them with a drop of a 1 per cent, chloral hydrate solution, which 

 gradually slows their movements without quickly killing and disinte- 

 grating them. Observe among other things their ciliary movements and 

 the various elemental organs within. Make careful drawings of these 

 animals, with all discernible detail, at intervals if necessary to indicate 

 changes. Paramecium merits all the observation and study that may 

 be put upon it. Parker in his Biology has an excellent description of 

 this animal as well as of others of like interest. See Jennings for the 

 mental processes of Paramecium, and Conn. 



The infusoria are so named because they appear in multitudes in the 

 course of a week or two in infusions of hay, dead leaves, and similar 

 nutritious substances. Ameba is the most difficult to be sure of having 

 at any given time, and Stentor is often scarce; but Vorticella, Tubifex, 

 the Rotifers, Cyclops, and Daphnia (the second a worm and the two 

 last crustaceans) can generally be found in balanced aquaria from 

 which fish and large larvae are absent. Cyclops and another crustacean, 

 the bivalved Cypris (of little use to us because its shells are opaque), 

 are much easier to keep year after year than is Daphnia; nearly every 



