INVITED SPECIAL PAPER: History of the botanical teaching laboratory in the United States

The establishment of teaching laboratories for botany in the United States was strongly influenced in the early part of the 19th century by the founding of a laboratory of natural history at the Rensselaer School by Amos Eaton who inspired numerous educators, particularly women. By midcentury and later, botany programs were established at land-grant colleges and the so-called “new Botany” movement spread from them. In the latter part of the century additional changes were brought about by the influence of German laboratory activity and botanists’ reactions to the introduction of the Huxley-Martin biology programs to America. During these times, Americans were improving their own manufactured microscopes, laboratory supplies, and equipment capabilities. By the beginning of the 20th century, laboratory teaching of botanical subjects was widely accepted as normal in universities and colleges, as well as in some high schools.     

Duty or dream? Edwin G. Conklin's critique of eugenics and support for American individualism

This paper assesses ideas about moral andreproductive duty in American eugenics duringthe early twentieth century. While extremeeugenicists, including Charles Davenport andPaul Popenoe, argued that social leaders andbiologists must work to prevent individuals whowere ``unfit' from reproducing, moderates,especially Edwin G. Conklin, presented adifferent view. Although he was sympathetic toeugenic goals and participated in eugenicorganizations throughout his life, Conklinrealized that eugenic ideas rarely could meetstrict scientific standards of proof. Withthis in mind, he did not restrict his eugenicvision to hereditary measures. Relying onhis experience as an embryologist, Conklininstead attempted to balance more extremeeugenic claims – that emphasized the absolutelimits posed by heredity – with his own view of``the possibilities of development.' Throughhis critique he argued that most human beingsnever even begin to approach their hereditarypotential; he moderated his own eugenicrhetoric so that it preserved individualopportunity and responsibility, or what hasoften been labeled the American Dream.     

NMR spin exchange kinetics at equilibrium in membrane transport and enzyme systems

A set of differential equations is formulated to describe the rapid exchange (time scale, approximately 0.01 to approximately 10 s) of a labelled solute across the membranes of cells in suspension. The labelling is achieved with nuclear magnetic resonance by exposure of the system to a high intensity radio-frequency pulse, and the excited nuclei relax to the equilibrium state with a short half life. An analytical expression for the decay of the magnetic resonance signal is presented; the solution involves the determination of eigenvalues, of an array of Laplace-Carson transformed differential equations, by use of the general solution of a quartic polynomial. Simulations of the behaviour of the exchange system using various conditions of cell number, rate constants and nuclear magnetic relaxation times are presented. The marked concentration dependence of the extent of reaction at a given time has not previously been reported for nuclear magnetic resonance exchange systems and is a feature anticipated from the known saturability of several membrane transport systems including glucose transport into human erythrocytes. The theory is readily generalized to other model systems by appropriate reinterpretation of the physical meaning of various parameters; the general form of the solution holds in many biological contexts other than membrane transport and includes equilibrium enzyme kinetics.