Seeds in a rainforest soil and their relation to shifting cultivation in the Ivory Coast

In the Taï region of the Ivory Coast, mature forest is felled and burned and a crop of rice is grown; forest is then allowed to regenerate for 20 or more years before being cropped again. The top 10 cm of soil beneath a 21-year-old forest prior to felling contained 2000 viable seeds m^?2 of mainly woody species of previous successional stages no longer represented in the vegetation. Seedling emergence was greater in full sunlight than under leaf canopy, especially for herbaceous species of open habitats. Burning destroyed almost half of the seeds, but overall germination of those that survived was advanced by about 2 weeks. Germination of some common pioneer species was enhanced by the fire. Provided that burning took place and the rice was planted immediately, vegetation arising from the seed bank did not present a problem. The density never exceeded 70 seedlings m^?2 and little or no weeding was required. Species present at densities greater than 1 seedling 10 m^?2 were all recorded in the seed bank.     

The correlation between the cytology of the vaginal smear and the time of ovulation in the bitch

The correlation between the vaginal smear and the calculated time of ovulation was studied in 22 bitches, during a total of 24 heat periods. Blood plasma was analysed for levels of oestradiol and progesterone from 6 days before to 6 days after the day of maximum keratinization of the vaginal smear. In all 24 heat periods (100 per cent) maximum keratinization of the vaginal epithelial cells was observed at least 3 days after peak oestradiol levels and in 17 of the heat periods (70.8 per cent) maximum keratinization was seen when the peripheral plasma level of progesterone had increased to >5.44 ± 0.93 ng/ml, which has been calculated as the ovulatory level.     

Genotypic frequencies of phosphoglucose isomerase allozymes in bean rust (Uromyces appendiculatus) populations estimated by densitometry

Phosphoglucose isomerase (PGI) is a dimeric enzyme in germinating urediniospores of Uromyces appendiculatus. Three distinct bands occur in heterozygous isolates after starch gel electrophoresis. Transmission densitometry was used to estimate the frequency of the homozygous slow (S), homozygous fast (F), and heterozygous (H) individuals in mixed preparations of urediniospores. Areas under each band peak were transformed to genotypic frequencies by comparison with standard 1:1 (F:S)and 100% H preparations. Estimated genotypic and allelic frequencies in prepared mixtures were linearly related to the actual frequencies. Correspondence of estimated with actual frequencies was high, generally differing by 10% or less. Three of 10 field collections examined were polymorphic for PGI allozymes, and two of these were apparently in Hardy-Weinberg equilibrium.     

HYSTEROGRAPHY IN THE BITCH

Using a previously described technique for catheterization of the uterus in the bitch, hysterography was performed on 26 of 28 bitches. The essentials of the technique are described, and the hysterographic findings in normal animals in various stages of the estrus cycle and also after experimental estrogen treatment are reported. Examples are also given of hysterograms of animals being investigated for infertility or showing clinical signs of metritis or ovarian endocrine disorders, hyperestrenism.