100 YEARS AGO

The possessors of certain hereditary characters are unquestionably sub-prolific; that is, they eventually contribute less than their average share to the stock of the future population. It may be that they die before the age of marriage, or that they are sexually unattractive or unattracted, or that if married they are comparatively infertile, or that if married and fertile the children are too weakly to live and become parents. It is very probable, though I have no trustworthy facts to confirm the belief, that persons affected with hereditary insanity are sub-prolific because their families, if they have any, are apt to contain members who are afflicted in various ways that render them less likely than others to live and to marry. But I do not propose to go into the details of this or of any other malady, but merely mention it as an illustration of what is meant, when I assume that the possessors of some particular characteristic, not necessarily a morbid one, and which may be called A, are sub-prolific on the average.

From Nature 11 May 1899.

50 YEARS AGO

Reports of tumours in insects are relatively rare. Paillot mentions proliferation in the fat cells of Euxoa segetum Schiff., following infection by virus diseases (pseudo-grasseries I and II). Tumours have been described in the fruit-fly, Drosophila melanogaster Meigen, by Stark and Russell: in larvae of the Pygaera group of butterflies, by Federley; and in the stick insect, Dixippus morosus Br., by Pflugfelder. They have been found in a large Orthopteran insect, Leucophaea maderae F., by Scharrer. All the tumours so far discovered in insects are apparently non-malignant, although malignancy has been claimed by Stark and Federley. Russell found that those in Drosophila reported by Stark as malignant were similar in structure to benign tumours occurring in the same insect, and that the so-called malignant tumours could be successively transplanted without hampering the development of the host. The tumour strains discovered by Federley apparently have been lost. Various stimuli will provoke tumour proliferations in insects. Spontaneous tumours occur in several genetic tumour strains in the fruit-fly, but the stimulus is not known.

From Nature 14 May 1949.