(1) Using a new type of culture ponds ("open bubbling sytem") according to the principle of Gummert et al., various strains of unicellular algae were grown outdoors without artificial regulation of culture temperature. (2) It was found that, with adequate algal strains, an average daily yield of 16-17g/m2-day (maximum 22-28g/m2-day) was obtainable in summer time, and 2-2.8g/m2-day (maximum 3.3g/m2-day) in winter time. The highest and lowest yield were obtained in August and January, respectively. (3) The advantages and disadvantages of the culture method used, as compared with the other methods thus far proposed for outdoor mass-culturing of algae, were discussed in detail.
(1) Using a simple method of test cultures, seasonal variation of growth rate of various strains of unicellular algae under natural light- and temperature -conditions was investigated. (2) The strains of ordinary temperature tolerance ("mesophilic"), such as Chlorella ellipsoidea, showed positive growth in all months throughout the year, although their growth was considerably suppressed in the hottest month, August. In contrast, the thermophilic strains grew actively in summer months, but showed no growth in winter months, December, January and February. (3) Taking into consideration the quantity of solar radiation and the energy content of algal cells, the efficiency of solar energy conversion shown by some algal strains was calculated. In the case of Chlorella ellipsoidea the efficiency (on a total radiation basis) was highest in October and November (5.3 percent) and lowest in January and August (1.3-1.4 percent). (4) It was shown that the growth rate of algae determined by the test cultures agreed fairly well with the actual yield obtained from the open outdoor cultures in each season. It was inferred that from large-scale outdoor cultures using mesophilic and thermophilic strains adequately according to the season, a yield of 18 metric tons (dry weight) of algae may be obtained per acre per year.
Twenty two chemicals were tested for their effectiveness in killing daphnids, and at the same time their maximum innocuous concentrations towards blue green algae were determined. It was observed that diethyl-p-nitrophenylthiophosphate is most effective as a daphnidkiller, and is, at the same time, innocuous for the growth of blue-green algae. For several years Parathion or Folidol, which is innocuous for the rice plant in a concentration of 250ppm, has been used as an insecticide in rice fields, and now it is also shown to kill daphnids in a concentration of 0.00075ppm. Assuming that the depth of the water in a paddy field is 10cm, the volume of water is 400, 000liters per acre. If the diluted solution of only 20ml Parathion is sprayed on this field, the concentration of the drug in the water of the field will become 0.05ppm. This concentration is about one hundred times the minimum lethal concentration of daphnids, and therefore this drug is remarkably efficient. It should be remembered, on the other hand, that daphnids are known to be a favourite food for fresh-water fish. If daphnids are killed by spraying of the drug on the paddy field sooner or later it may affect the growth of fresh-water fish in the paddy field water by the continued scarcity of daphnids.
1. The mycological characters of 172 anti-trichomonal Actinomycetes, which had been selected from 1244 typical Actinomycetes, were studied, and their belonging 9 groups, 12 specics, and 3 new species is described. Among them the S. lavendulae, S. reticuli, S. diastatochromogenes, and S. griseus groups had large numbers of strains as shown in Table 1. However, some of the cultures of the S. diastatochromogenes group and the S. ruber group quickly lost their activity after repeated transfers on synthetic medium (Table 4). 2. Morphologically these Actinomycetes may be divided into four sections, and, as shown in the text, further classified by using the color of the aerial mycelium, soluble pigment production, and the color of vegetative growth as keys. 3. Strains H-5080, H-4871, and H-4650 were considered to be new species and were named S. purpeofuscus n. sp., S. naganishii n. sp., and S. griseoruber n. sp., respectively. 4. The antibiotic spectrum, the dilution potency, and the haemolytic power of these Actinomycetes were examined. 5. Carbon utilization of typical anti-trichomonal Actinomycetes was studied (Table 3).