_Note._--To find answers to many of these questions it will be necessary to refer to the reference books in the laboratory. 1. Examine a specimen of Volvox. Why may this be considered a colonial protozoan and not a many-celled animal? What is gained by the colonial habit? 2. Is the colonial habit common or rare in sponges and cœlenterates? What is chiefly gained? 3. Describe the community life in one of the insects in each of the following groups:-- a. ant, honeybee, termite. b. bumblebee, paper wasp, hornet. c. mining bee. d. carpenter bee, mud wasp, digger wasp. 4. Name the host or hosts in the following cases: trichina, liver fluke, malarial parasite, tapeworm, hook worm. Give the life history of one or more of the parasites just enumerated. What is the effect of parasitism on the structure of the parasite? 5. What is the relation between ants and plant lice? Show how this relation is mutually helpful. Mention other cases of symbiosis that you have come across. 6. With what animal are barnacles often associated? What is the habit of the pea or oyster crab? What are "guest bees"? What structure is lacking that is found in other bees? What are often found in the cavities of sponges? Why are these associations called commensalism rather than symbiosis? _Summary._ 1. Into what groups can animal associations be divided based upon the number of species concerned? 2. From the standpoint of protection, is this a good or a bad method of protection? 3. What disadvantages can you see in this method of protection. #D. PROTECTIVE HABITS AND POWERS# _Materials._ Specimens, charts, and books, showing habits of invertebrates. _Definitions._ _Regeneration_, the power to grow new parts of the body when parts have been lost or injured. _Masking_, the covering of an animal by some object or organism so as to hide its identity. _Nocturnal habits_, the habit of hiding in the daytime and coming out at night to feed. _Terrifying attitudes_, the protective attitudes assumed at times by animals in order to ward off attack. _Observations and questions._ 1. How are Sabella and Serpula protected? What advantages and disadvantages in this habit? What changes in structure are associated with this tube-dwelling habit? 2. What two protective habits has the earthworm? Name some other animals that have similar habits. 3. Describe the protective habits of the caddis-fly larva; of the leaf-roller moth. What benefit to the hermit crab is the colony of hydractinia growing on the snail shell which it inhabits? Give other similar cases. 4. Name as many cases of regeneration as you can. 5. What peculiar habits has a puss-moth larva? a dragon fly? Give other examples. _Summary._ 1. Name the various protective habits. 2. State any advantages or disadvantages you can with reference to these protective habits. #E. DEFENSIVE STRUCTURES# #Another Method of Protection from Enemies# _Materials._