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A new design for experiments in the general chemistry laboratory incorporates a "do-it-yourself" component for students. In this design, students perform proven experiments to gain experience with techniques for about two-thirds of a laboratory session and then spend the last part in the do-it-yourself component, applying the techniques to an experiment of their own design. An emphasis on classifying inorganic reactions as acid-base, redox, complexation, and precipitation supports this program. An example is an enthalpy of reaction experiment in which students study an acid-base reaction, a complexation reaction, a precipitation reaction, and a redox reaction. Students perform three of the proven reactions and then do the fourth type with a reaction of their choosing. Other examples of experiments are described. The do-it-yourself component engages students in design and interpretation within a reasonable framework. With this approach, students take chances with new ideas as do working scientists.

Beetles were milked of their abdominal defensive secretion at three different frequencies over the first 36 days of adult life. Secretion production decreased greatly with age from a maximum of 94 nmol/day at 4–6 days to a basal level of about 25 nmol/day at 30–40 days. Ethyl- and methylquinone comprised the bulk of the secretion and were most strongly affected by age. Benzoquinone was most strongly affected by milking frequency. An average adult produced an estimated 4445 nmol of total secretion in its 5-month life-span but had reservoirs large enough to store 11,000 nmol. Males produced more secretion than females because of their larger size and inherent sexual differences. As they aged, mated females showed a more rapid decrease in production that virgin females. The defensive system appears to be programed to charge glands rapidly with secretion early in adult life and fall of to a low recharge rate little affected by discharge.