A Note on the Development of a Technique for Regeneration of a Degenerated Culture

In a heterogeneous degenerated culture the method of in situ screening of established agar colonies (the number screened being limited) cannot reveal the presence of an antibiotic-producing organism even after mutagenic treatment, whereas the close-range parallel streak method can succeed. Streaking a pour-plate culture of an antibiotic-sensitive organism by parallel streaks of mutagen-treated inactive culture of the once producer afforded a better chance for regeneration of a degenerated culture.     

COMPARATIVE STUDIES OF PHOTOSYNTHETIC PROCESSES IN ORDINARY AND FULLY DEUTERATED ALGAE

The light-saturated growth rate of fully deuterated algae hasbeen found less than that of ordinary algae by a factor of threeto four. However, as compared to the net rate of photosynthesis,the Hill reaction rate indicates an unimpaired light reactionsystem. Analysis of cell extracts for amino acid content and¹⁴C-uptake studies indicate a decreased utilization of the productsof photosynthesis by deuterated algae, probably because of agenerally lowered protein metabolism. We conclude that in algaeD₂O does not have a pronounced effect on the light reactionin photosynthesis. ¹ Based on work performed under the auspices of the U. S. AtomicEnergy Commission.² Resident Research Associate, 1962–64.³Present address: University of Illinois, Department of Pharmacy,Chicago, Illinois.     

EFFECTS OF FLOW RATE ON TASTE INTENSITY RATINGS

The effects of stimulus flow rate on perceived taste intensitywere studied in man using five concentrations of each of fourstimulus compounds (sodium chloride, hydrochloric acid, quininehydrochloride, and sucrose) and six different flow rates from1.2 to 12.0 cc/sec. AH stimuli were presented through a tonguechamber. Perceived taste intensity increased monotonically withflow rate for every stimulus condition tested. Psychophysicalfunctions calculated across flow rates (rather than across physicalconcentrations) support the view that flow rates mimic physicalconcentration.     

Use of a Chemical Sanitizer for Cleaning Fish Boxes

A number of organic, inorganic and surfactant substances were tested for their cleaning efficiency, ability to reduce bacterial load and deodorize fish boxes. A 0.1% iodine solution had good bactericidal and deodorizing properties, whilst a number of surfactants, especially the quaternary compound Quat-LTM, had good cleaning and bactericidal properties. None of the substances used possessed all three desirable properties sought for in this study.     

Clitellate cocoons in freshwater deposits since the Triassic

Previously enigmatic, ovoid to sac-like fossils of organic, acid resistant substance which are common components of leaf cuticle and megaspore assemblages in limnic and terrestrial palaeoen- vironments are identified as cocoons of clitellates. They have been recorded for a long time by palaeobotanists and palynologists, particularly in the Mesozoic, and have been variously interpreted as being of megaspore, seed, or algal origins, although convincing homologues were lacking. The fossils agree in basic wall construction with cocoons of clitellates, and particularly with certain members of the Hirudinea. A clitellate affinity is further supported by a possible segmentation, their consistently non-marine occurrence, evidence for predation, and an example of amber-like inclusion of alien structures in the cocoon wall which indicates the presence of secretion. As a consequence of the new interpretation, two taxa established under the botanical code of nomenclature for such fossils, namely Burejospermum crassitestum Krassilov and Dictyoth- ylakos pesslerae Horst, are transferred to the zoological kingdom and classified under Clitellata (phylum Annelida), along with two new taxa, D. spitsbergensis sp.n. and Pilothylakospilosus gen. et sp.n. With the present interpretation a consistent Mesozoic record is documented for clitellates, a group of softbodied, basically freshwater and terrestrial animals of which there was until now nearly no fossil record.