THE INCIDENCE OF BACTERIUM COLI IN FARM WATER SUPPLIES

SUMMARY: Farm water supplies giving 37° positives in MacConkey's broth within 24 hr. had a much higher incidence of presumptive Bact. coli type I than those which gave 37° positives during the second day of incubation only; presumptive Bact. coli reactions were obtained with 85% of the 7,522 tubes positive in 24 hr. compared with 23% for the 7,593 tubes showing positive reactions during the second day at 37°.     

The Ovule and 'Seed' of Araucaria Bidwillii with Discussion of the Taxonomy of the Genus: III. Anatomy of Multi-ovulate Cone Scales

This paper deals with the anatomy of two- and three-ovulatecone scales which are found occasionally in the cones of A.Bidwillii. The manner in which each ovule receives its vascularsupply from bundles lateral to the ovule is discussed, togetherwith a hypothetically primitive type of araucarian cone scalewith three ovules possibly resembling the fossil Schizolepis.The interpretation of the vascular system of the scales as givenin this paper is a correction of that presented in the firstpaper of this series by the same authors.     

Dinosaur stampede in the Cretaceous of Queensland

Numerous and well-preserved trackways in mid-Cretaceous sediments of West Central Queensland, Australia, are attributed to a stampede of small to medium-sized bipedal dinosaurs - both herbivores (ornithopods) and minor-league predators (coelurosaurs). The tracks of a single large predator (carnosaur) suggest a reason for the stampede. These trackway data permit calculation of sustained running speeds for the coelurosaurs and ornithopods.     

EFFECT OF TETRACHLORONITROBENZENE ON THE SPROUTING AND CROPPING OF POTATO TUBERS

Potato tubers dusted with a preparation containing 3% tetrachloronitrobenzene (TCNB) and kept in a nearly closed container in the laboratory showed reduced sprouting. The reduction was greater the lower the temperature and the earlier the application of the dust; it was less marked with tubers lying on a moist substratum. After long exposure, and especially at higher temperatures, sprouts of treated tubers tended to show a 'witch's-broom' appearance. The repressive effect of TCNB on growth rate disappeared as soon as the tubers were brought into ordinary air. To a certain extent the action of TCNB was antagonized by treatment of the tubers with ethylene chlorhydrin.
Replicated field experiments over three seasons, with four potato varieties, gave a measure of the check to bulking of the crop which is brought about by winter storage of seed tubers in presence of TCNB. This check was eliminated by airing the tubers before planting, the time necessary for this depending on conditions. An airing period of about 6 weeks, in an unheated greenhouse (apart from sun- heat) was found to be sufficient for this purpose.
The speed of emergence of the variously treated batches was closely correlated with the yields produced, especially in the earlier liftings.
The average number of shoots per plant was significantly increased by the dust treatment and this was reflected in a higher seed/ware ratio in the mature or late-lifted crop.
There was no evidence that the delay in sprouting brought about by TCNB was due to an effect on the respiration rate of the dormant tubers.
The concentration of active principle was materially diminished in treated clamps after the period ( c. 5 months) of winter storage. Estimates were also made of the persistence of TCNB on exposed surfaces in still and in moving air.     

Multicellular Pollen Formation in Cultured Barley Anthers: I. INDEPENDENT DIVISION OF THE GENERATIVE AND VEGETATIVE CELLS

Multicellular pollen units partitioned into embryo- and endosperm-or possibly suspensor-like components are formed in barley (Hordeumvulgare cv. Sabarlis) anthers cultured from spikes excised duringthe free spore phase of microsporogenesis. The embryo-like componentmay be derived from the generative cell, the vegetative cell,or from contributions of both cells, and appears to be usually,though not invariably, haploid. The endosperm- or suspensor-likecomponent is derived from the vegetative cell and rapidly becomesnon-haploid or mixoploid. The initial pattern of division oftensimulates that in the formation of 4-celled and 7-celled embryosacs. The time of excision during the free-spore phase is critical.Partitioning occurs only with excision during the mid-unicellularstage (stage 2) when the nuclei are probably still in the pre-DNAreplication phase, but excision at the early unicellular stage(stage 1) in ineffective and leads to rapid degeneration ofthe spores. With excision at the late-unicellular stage (stage3), independent contribution by the generative cell is blockedand the pollen develops by the known A, B, or C pathways. Temperaturestress given to the excised spikes before culture of the anthersenhances the frequency of partitioned units but is thought notto be causal. It is suggested that the multiplicity of developmentalpathways may have some bearing on whether the plantlets ultimatelyproduced are albino, variegated, or green.