THE KARYOTYPES OF DIPLOID CESPITOSE ZINNIAS: A METHOD AND ANALYSIS

The karyotypes of the three diploid (n = 10) species of the subg. Diplothrix (Zinnia—Compositae) were compared to determine whether there were any demonstrable differences which could then be sought in their polyploid derivatives. Because many of the chromosomes in a set were too similar to distinguish confidently between them, a method of analysis was developed which measures the similarity of whole sets of chromosomes rather than individual ones. The method consists of measuring the distances between graph-plotted vertices representing arm lengths of chromosomes of real or paper hybrids and then comparing these distances by means of U tests with those similarly derived for the “parents.” This procedure obviates the need of attempting to identify morphologues (morphologically similar chromosomes) in a somatic diploid root-tip cell and to equate corresponding pairs of chromosomes from different cells of a single plant or from different species or hybrids. No demonstrable differences in the karyotypes of diploid cespitose zinnias were found. Analysis of previously published data by this method indicated that there has been a general non-objectivity and non-operationalism in the determination of homologous chromosomes, and a general but unwarranted assumption that morphologues are in reality genologues (genetically corresponding chromosomes).     

PERFORATED PEPTIC ULCER—Selective Gastric Resection in Emergency Treatment

In a series of 240 cases of perforated peptic ulcer prior to 1952 there was a total mortality of 17 per cent. This included cases treated conservatively as a planned procedure or because of other morbid conditions and undiagnosed cases, all ending in death.In cases treated by simple suture, mortality was 2.6 per cent for patients under 50 years of age and 17 per cent for those over 50, the rate rising very steeply with each decade over 50.From 1953 through 1959 selective gastric resection was carried out, the operation being done in all cases of perforated gastric ulcers, of chronic duodenal ulcers and of perforations associated with hemorrhage.During this period 303 perforated ulcers were treated, with a mortality of 15.5 per cent. Patients with associated morbid conditions and those admitted moribund and died, or died undiagnosed were again included.In this series also the mortality increased steeply from age 50 onward.Gastric resection was carried out in 148 cases of perforated peptic ulcer with a mortality of 6 per cent. In 105 cases under 60 years of age there were no deaths but in those over 60 the mortality rate was 21.8 per cent. Results in the patients who had resection, as determined after three years of observation, compared favorably with the results in patients who were treated by suture.The mortality of perforated ulcers in females was higher than in males.Emergency gastric resection has a definite place in the treatment of perforated peptic ulcer.     

Age,Experience, and the Response of Streamside Salamander Hatchlings to Chemical Cues from Predatory Sunfish

Previous work has shown that streamside salamander larvae (Ambystoma barbouri; Ambystomatidae) exhibit an adaptive ‘sink to the bottom’ response to chemical cues from predatory green sunfish (Lepomis cyanellus; Centrarchidae), that is, larvae sink to the bottom more quickly (thus minimizing exposure time to sunfish predation) when they are dropped into water with sunfish chemicals (as compared to Ashless controls). Here, we examined this anti-predator behaviour in early hatchlings and the effects of age and experience on subsequent expression of this behaviour. Hatchlings responded significantly to fish chemical cues within the first 18 h after hatching. Age did not significantly influence this response, i.e. regardless of age (1, 7, or 14 days after hatching) larvae showed a significant response during their first exposure to fish chemical cues. Experience also did not significantly influence the larval response to fish chemicals i.e., repeated exposures over 2 weeks did not significantly influence the magnitude of the response. Finally, comparisons of 3 siblingships detected significant variation among siblingships that might reflect genetic variation in this behaviour.     

Subject: Endocrinology and chronobiology

Research Notes on Avian Biology 1994: Selected Contributions from the 21st International Ornithological CongressMorphology and Physiology: Endocrinology

Subject: Endocrinology and chronobiology