Describes a single technique for an enzyme assay of catalase. The method shows that vegetable seeds submitted to pre-sowing 'hardening' cycles of imbition and drying have greater catalase activity and more rapid germination than do the controls. (LS)

Suggestions for instructional improvement are provided in two topic areas. Explains the use of models in helping students to visualize selected concepts in genetic engineering and recommends the use of tropical tuber crops for encouraging students to conduct practical investigations. (ML)

Clearing is a simple and rapid technique in which 75 percent lactic acid is used to remove pigments and cytoplasmic contents of fresh leaves, enabling microscopic view of various internal leaf layers. Procedures for using the technique (which helps students gain a more thorough understanding of plant anatomy) are given. (DH)

Describes a field exercise which links ecology and taxonomy in the teaching of the species concept. Two common hedgerow plants (red and white campions) are used as a pair of "species" that are normally distinct. Plants of intermediate character can be encountered, and the status of these plants is investigated. (Author/JN)

Described is an experiment investigating carbon dioxide fixation in the dark and the diurnal rhythm of acid production in plants exhibiting Crassulacean Acid Metabolism. Included are suggestions for four further investigations. (SL)

Describes the experimental procedures for isolating fungi and demonstrating their tolerance of fungicides such as creosote and organic mercury. (JR)

Describes techniques and results of a study on leaves of a leguminous tree. (PS)

Describes equipment for recording human breathing (stethographs, tambors, spirometers), construction of pooters (pipettes), field exercise on examining epiphyte distribution on tree bark, and vertebrate skeleton models for teaching locomotion. Includes abstract of student research project examining pH on Colpoda encystment and reviews of…

Offers suggestions for teaching some aspects of water economy in plants. These include diffusion/osmosis, water transport, the part played by turgor in structural support, and its implications for plant organs or whole plants. Several practical demonstrations/experiments are also described. (JN)

Reviews methods for obtaining accurate and reproducible results in determining zonation patterns on rocky shores. (CS)

Describes a modification in the use of artificial substrates to study attached micro-algae. Apparatus is based on glass microscope slides immersed in natural water environments; biomass and primary productivity are assessed by measurement of alpha-chlorophyll. Describes use in studies of colonization, succession, and populational fluctuation. (CS)

Described is a simple technique to monitor air pollutants and to simulate some of the features of roadside canopies. Included are the procedures, directions for the assembly of the apparatus, and a discussion of typical results. Graphs of sample data are presented. (CW)

Describes laboratory procedures for observing the progressive change deciduous leaves undergo prior to abscission. Outlines the starch test, sugar test, extraction and chromatography of pigments, and experimental results. States that obtained results enable the events of leaf senescence to be correlated with the carbohydrate economy of a tree in…