An automated technique for monitoring carbon dioxide respired by insects*

ABSTRACT. A non-dispersive infrared gas analyser equipped with a Luft-type sonic detector and flow-through reference cell was automated to monitor the total volume of carbon dioxide (CO₂) respired by single insects or groups of insects. The infrared analyser was interfaced with an integrator for quantification, a microprocessor to control intermittent air flow through the insect respiration chambers, and a microcomputer for data storage and reduction. This technique has been used to monitor the CO₂ Output of diapausing and non-diapausing mature fifth instar larvae and of developing pupae of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). The resulting data were accurate, quantitative and reproducible.     

The Ultrastructure of Myosin-Extracted Striated Muscle Fibers

Electron microscope examination of myosin-extracted psoas muscleof the rabbit reveals a number of thin filaments, about 25 Äin diameter, bridging the gap between the ends of the actinsand the remaining myosin of the M band. Extraction of actinfrom the region of the Z disc shows similar thin filaments nearthe Z disc. Myosin-extraction of several invertebrate musclesreveals a remaining network of thin filaments in the regionof the A band. These thin filaments are probably elastic, andcould contribute to the functioning of these muscles.     

An aquatic microfossil assemblage from Cenomanian amber of France

The ‘osseous’ amber from the Cenomanian of northwestern France contains numerous microscopic inclusions, some of which are fairly well preserved and identifiable as protists. This paper describes three cyanobacteria similar to modern Plectonema. Lyngbya, and Coelosphaeriunr, fungus-like fossils of uncertain affinities (cf. ?Candida); a colorless chrysomonad similar to Monas; a desmid identical with Closterium; and naked ciliates of uncertain affinities (cf. Cyrtolophosis). All of these fossils are in a single sample of amber from Bretagnolles (Eure Département). This assemblage is comparable to modern limnetic microbial communities. It is typical of shallow freshwater environments in which productivity and respiration are both high. This interpretation fits paleoecological reconstructions drawn from the arthropod fossils from French amber. ***Chrysomonads, ciliates, Cretaceous, cyanobacteria, desmids, fungi, micropaleontology.