Abstract: Methods of random amplification of polymorphic DNA are provided which comprise the use of concentrations of nucleotide triphosphate reagents at concentrations of from 0.4 to 0.6 mM. Magnesium is also used according to:?Mg!=?ATP!+?GTP!+?TTP!+?CTP!+1.5.+-.0.3 mMpH is controlled by Tris HCL at 10 mM and KCl at 50 mM with a pH of 8.8 to 9.0. Heat resistant polymerase enzyme is used at a concentration of 0.7 units per 13.5 .mu.l reaction volume. The concentration of oligonucleotide primers is selected to be from 0.4 to 0.8 .mu.M. When more than one oligonucleotide primer is used a stoichiometry of from 1:1.25 to 1:0.8 is used. Mathematical modeling is used to describe the distribution of numbers of polymorphisms produce per primer, combined Poisson and binomial distributions are used to describe the frequency distribution of polymorphisms over a number of different primer molecules, and the fraction of primers mean value (F.sub.

Abstract: An aqueous medium for plant tissue culture is provided including a nutritively effective concentration of reduced nitrogen, preferably in the form of an amino acid such as arginine employed in an amount of from 1.0 to 5.0 mM, and having not more that 1.5 mM NH.sub.4.sup.+. A phosphorus compound at a concentration of at least 2.5 mM measured as phosphate is also included. A chelating agent such as EDTA, and an iron compound present in molar excess over the concentration of the chelating agent are employed to control divalent ion concentrations. Potassium ions are maintained at a concentration of below 14 mM. The use of media containing ammonium ions at less than 1.5 mM combined with a supply of reduced nitrogen in the form of arginine, with low potassium levels, has proved useful as media for organized growth, particularly for use with coniferous plants.

Abstract: Apparatus for treating human joints wherein a machine reciprocates to flex the joint while an electrical stimulator causes contraction of muscles affected by the flexing. Switches disposed along the path of machine movement are tripped to energize the stimulator current during selected stages of the machine movement, and in either or both directions.