100 YEARS AGO

In India, as elsewhere, the general doctrine of disease prevails that all abnormal and morbid states of body and mind are caused by demons, who are conceived either as attacking the body from without, or as temporarily entering the body of man. The consequence is that primitive medicine consists chiefly in chasing away or exorcising these hostile spirits. This is done, in the first instance, by charms. The spirit of the disease is addressed with coaxing words and implored to leave the body of the patient, or fierce imprecations are pronounced against him, to frighten him away. But these charms, powerful as they are (in fact, there is nothing more powerful to the primitive mind than the human word, the solemn blessing or curse), are yet not the only resource of the ancient physicians or magicians. From the earliest times people had become aware of the curative power of certain substances in nature, especially of herbs. ⃛ The principle that similia similibus curantur prevails throughout the whole range of folk-medicine. Thus dropsy is cured by water.

From Nature 7 July 1898.

50 YEARS AGO

Previous methods do not appear to give any indication of how to distinguish between young and old Colorado beetles, except during the first few days following the emergence of the young beetle. I have found evidence that it is possible to separate young and old beetles for a period of at least fourteen days after the emergence of the young adult by means of colour changes in the membranous wings. This fact is of considerable practical importance and assistance to entomologists, especially in countries where the beetle has not yet become an endemic pest. ⃛ The membranous wings of the fresh emergent are transparent and devoid of colour, while those of the mature beetle are red except for the apex and anal border of the wing. The wings remain colourless for at least four to five days after emergence, and afterwards develop a pink colour which gradually deepens and diffuses over the greater part of the wing surface ⃛ until the pink colour has given place to a distinct red hue.

From Nature 10 July 1948.