A new method of carrying out grafts of early embryonic chick limb buds to the chick chorio-allantoic membrane and a processing schedule which renders cartilage elements visible in whole mount are discussed, including implications for the procedures and their results. (Author/DC)

An experiment on the operation and utility of an amperometric immobilized enzyme electrode (or probe) is described, including advantages of the experiment, equipment, reagents, preparation of phosphate buffer, enzyme immobilization techniques, laboratory procedures, precautions, and discussion of experimental results. (SK)

Provides background information and problems with the formaldehyde clock reaction, including comparisons of experimental clock times reported in the literature and conditions for the reliable use of the formaldehyde clock based on a method discussed. (JN)

Experimental procedures are provided for the quantitative determination of Vitamin A (retinol) in food products by analytical liquid chromatography. Standard addition and calibration curve extraction methods are outlined. (SK)

Materials and methods are presented illustrating a modification of the Nakai/Glinsmann technique for comparing apparent formation constants for ADP-Mg and ADP-polyamine complexes. (Author/SK)

Describes experiment expanding on principles behind measuring efficiency of chromatographic columns and allowing calculation of parameters in the van Deemter equation. Easily accomplished in a three-hour period using a gas chromatograph in which gas flow can be changed and measured. Mathematical solutions can be attained with programmable…

An experiment using gas-liquid chromatography is discussed, introducing the student to concept of dead volume and its measurement, idea and use of an internal reference compound, and to linear relationship existing between measurements of a separation on two different stationary phases. (Author/SK)

Compares and contrasts effects of two spectroscopic techniques on bromine and iodine vapor. (CS)

Presents nine physics notes for British secondary school teachers. Some of these notes are: (1) speed of sound in a steel rod; (2) physics extracts-part four (1978); and (3) a graphical approach to acceleration. (HM)

Describes some undergraduate laboratory experiments in acoustics which involve the analysis of speech and musical instrument sounds and the general analysis of the frequency range of complex sounds. (HM)

Presents experiments that illustrate some physiologically important aspects of ligand binding to hemoglobin. (CS)

Describes a technique for the supercooling of water, for use in the science classroom, involving adding common salt to a mixture of ice and water. Several investigations are included for use during (and after) the process of supercooling. (DS)

Outlines procedures for demonstrating and preparing a permanent slide of sister chromatid exchanges and recombination events between the two chromatids of a single chromosome. Provides the name of an additional resource for making preparations of exchanges. (RT)

Suggests specific ways in which laboratory activities might be slightly modified to increase students' understanding in science, based on recommendations from the National Science Education Standards and on constructivist understandings of the learning process. Contains 42 references. (WRM)

Presents a laboratory experiment on determining the molecular weight of an unknown molecule by using gel filtration chromatography. Describes the procedure and lists required materials. (YDS)