The growth of bacteriophage

1. An anti-Escherichia coli phage has been isolated and its behavior studied. 2. A plaque counting method for this phage is described, and shown to give a number of plaques which is proportional to the phage concentration. The number of plaques is shown to be independent of agar concentration, temperature of plate incubation, and concentration of the suspension of plating bacteria. 3. The efficiency of plating, i.e. the probability of plaque formation by a phage particle, depends somewhat on the culture of bacteria used for plating, and averages around 0.4. 4. Methods are described to avoid the inactivation of phage by substances in the fresh lysates. 5. The growth of phage can be divided into three periods: adsorption of the phage on the bacterium, growth upon or within the bacterium (latent period), and the release of the phage (burst). 6. The rate of adsorption of phage was found to be proportional to the concentration of phage and to the concentration of bacteria. The rate constant ka is 1.2 x 10–9 cm.8/min. at 15°C. and 1.9 x 10–9 cm.8/min. at 25°. 7. The average latent period varies with the temperature in the same way as the division period of the bacteria. 8. The latent period before a burst of individual infected bacteria varies under constant conditions between a minimal value and about twice this value. 9. The average latent period and the average burst size are neither increased nor decreased by a fourfold infection of the bacteria with phage. 10. The average burst size is independent of the temperature, and is about 60 phage particles per bacterium. 11. The individual bursts vary in size from a few particles to about 200. The same variability is found when the early bursts are measured separately, and when all the bursts are measured at a late time

Responses of Phycomyces indicating optical excitation of the lowest triplet state of riboflavin

Phototropic and light growth responses of the sporangiophore of Phycomyces have been elicited using tunable laser stimulation from 575 to 630 nm. The growth response shows additional components of the action spectrum with a sharp peak at 595 nm, a sharp cut-off at 585 nm, and a tail extending beyond 630 nm. The integral over the electronic transition (f-value) is 1.5 x 10^-9 times that at 455 nm. These parameters indicate a direct transition from the ground state to the lowest triplet state of riboflavin

Meiosis in Phycomyces

A four-factor cross between two strains of Phycomyces involving two auxotrophic, one color, and the mating type marker is described. Samples of 40 germspores from 84 individual fertile germsporangia were characterized. The results show: (i) The germspores of a germsporangium are derived from one meiosis in approximately 78% of the cases. (ii) The four markers are on separate chromosomes. They are nonselective. (iii) Analysis of a large sample of germspores from 106 pooled germsporangia confirms that the four markers are unlinked. (iv) From the ditype/tetratype ratios it is inferred that each marker is located about 15 map units from its centromere

Das Institut für Gährungsgewerbe und Stärkefabrikation in Berlin

DAS INSTITUT FÜR GÄHRUNGSGEWERBE UND STÄRKEFABRIKATION IN BERLIN Das Institut für Gährungsgewerbe und Stärkefabrikation in Berlin / Delbrück, Max (Public Domain) ( - ) Title page ( - ) Widmung: M. Delbrück (3) I. Allgemeines (5) II. Zur Geschichte der Vereine und des Instituts (8) III. Die Abtheilungen (12) Die technisch-wissenschaftliche Abtheilung (12) Die Abtheilung für technische Verwerthung des Spiritus (14) Abtheilung für Rohstoffe (16) Das analytische Laboratorium (17) Die botanisch-bakteriologische Abtheilung. (Abtheilung für Reincultur) (18) Die bau- und maschinentechnische Abtheilung (19) Die Unterrichtscurse des Instituts (20) Die Betriebsrevisionen (21) Die wirthschaftliche Abtheilung (21) Die Bibliothek (21) Die Veröffentlichungen (22) Die Glasbläserei (23) IV. Die praktischen Versuchsanstalten (24) V. Die Vereinsvorstände (29) VI. Die Beamten (31

Pauli Biographical Collection: Letter

Letter from M. Delbrück to W. Pauli

Pauli Biographical Collection: Manuscript

Manuscript by M. Delbrück. Comparison between atomic physics and molecular biology

Light and life III

[no abstract

Pauli Manuscript Collection: Confidential report

Report [to Pauli] of a discussion, may be between Max Delbrück, Niels Bohr and [?]. About a "famous" letter written by [N. Bohr] to [W. Pauli]

La materia e la mente: lezioni di epistemologia evolutiva

La mente nasce dalla materia ? Da questa domanda scaturisce il viaggio attraverso la scienza, all'origine di questo libro, che Max Delbrück proponeva ai suoi studenti in California