100 YEARS AGO

Is there not room for some provisional hypothesis which shall include both Galton's and Mendel's ideas, which are not necessarily antagonistic, but may turn out to be as simultaneously true as the laws of Boyle and Charles, so that the final results may be of the nature of a product or resultant? I mean that instead of drawing a hard-and-fast line between “recessive” and “dominant” characters we may suppose that these differ like heat and cold, in degree but not in kind. ... To take an instance. Last year (1901) I carefully hybridised two varieties of the sweet pea, using lens, paint brush and muslin nets. One variety used was “Gorgeous,” of a salmon-orange colour. ... The other variety was a new cream white, Eckford's “Mrs Kenyon,” novelty of 1901. ... None of the flowers of the offspring have been cream-coloured; the seeds borne on “Mrs Kenyon” by pollen from “Gorgeous” have all yielded purple flowers unlike either immediate parents, but probably taking their colour from the known remote purple ancestor of our sweet peas. Of seeds borne on “Gorgeous” by pollen from “Mrs Kenyon,” eight plants yielded flowers like “Gorgeous” but ten of the plants yielded purple flowers. Here the dominant purple appears to be due to the previous long ancestry; the salmon variety of ten years' standing has several representatives, but not one single cream flower stands for the 1901 novelty.

From Nature 23 October 1902.

50 YEARS AGO

During the past two years, simple mud-walled, thatch-roofed huts fitted with exit window traps and occupied by volunteer Africans have been sprayed with various formulations of the three insecticides, DDT, BHC and dieldrin, and the effect on the Anopheles gambiae, A. funestus and culicine mosquitoes entering them observed. Daily mortalities among the mosquitoes were determined by counting the dead individuals on the floors of the huts, and counting those dying later (within 12 hr. of capture) which were caught alive inside the huts in the morning and in the window traps during the night. ... In the later experiments a hut was also treated with the new insecticide, dieldrin. This was applied in the form of a wettable powder at a calculated dosage of 50 mgm. dieldrin per square foot... . Results showed this insecticide to be the most efficient of those tested.

From Nature 25 October 1952.