AN INTEGRATING RECORDER FOR PHOTOSYNTHETICALLY ACTIVE RADIANT ENERGY WITH IMPROVED RESOLUTION

A device counting fixed amount of parcels of radiant energyefficient in photosynthesis (wavelength region 400 to 720 mµand recording their total as a digital reading on a counteris described. Radiant energy is transformed by means of a phototubeto electrical current which becomes divided into individualparcels by cycles of charging .and discharge of a condenserbetween two fixed values of potential, and the number of thesecycles is counted. From instruments of similar design published earlier the onepresented here is distinguished mainly (1) by improved linearityof response in the integrating circuit down to slow countingrates and (2) by the design of a nonselective detector (in thelimited range of wavelengths indicated) based on a vacuum emissionphototube, which may be combined with the simple integratingcircuit used. Thus totals of irradiance (throughout the rangeof intensities of solar radiation) may be obtained directlyin units of energy or in the number of quanta. A very reliable and stable receiver with energy proportionalresponse in the region of wavelength 400–720 mµ(with possible extension up to 1,000 mµ) was realizedusing a vacuum emission photocell with photosensitive surfaceof the double-peak emission type (covering the range from nearUV to near IR) and precisely counterbalancing its spectral sensitivitycurve by selective absorption glass filters. The RENTSCHLER's type integrating circuit with a cold cathodedischarge tube was improved by increasing the maximum countingrate on one side (damping germanium diodes across the coilsof relay and counter) and by minimization of leakage in parallelto spare condenser (the contact which shortcircuits the condensersimultaneously with ignition of the discharge tube). ¹ Dedicated to Prof. H. TAMIYA on his 60th birthday. (Received November 24, 1962; )     

Aspects of the biology of Hyolitha (Mollusca)

Hyolitha constitute an extinct group of class rank assigned to Molhsca. Two orders, Ortho-thecida and Hyolithida, are well established and most knowledge of morphologic detail is derived from the latter. Both orders had an operculum not hinged to the conch. Hyolithida also had paired, curved, whiskerlike appendages, requiring complex musculature to move them and the operculum. The Hyolithida were probably deposit feeders living in shallow water, and accordingly were tentaculate. A reconstruction of the soft parts of this sedentary organism is given — a shallow mantle cavity on the dorsal side, anterior tentacles, a long intestine, and a reduced ventral foot. Except for the more complex musculature associated with an elaborate operculum, Orthothecida are judged to have had a similar anatomy.