Page:Proceedings of the Royal Society of London Vol 60.djvu/342

Rh on. The Davy Medal is awarded to him in recognition of his great merits and achievements as an investigator.

The Darwin Medal for 1896 is awarded to Professor Grassi, of Rome (late of Catania), for his researches on the constitution of the colonies of the Termites, or White Ants, and for his discoveries in regard to the normal development of the Congers, Mursense, and Common Eels from Leptocephalus larvae.

From a detailed examination of the nature and origin of the colonies of the two species of Termites which occur in the neighbourhood of Catania, viz., Termes lucifgsand, he was able to determine certain important facts which have a fundamental value in the explanation of the origin of these and similar polymorphic colonies of insects, and are of first-rate significance in the consideration of the question of the share which heredity plays m the development of the remarkable instincts of “ neuters,” or arrested males and females, in these colonies. Professor Grassi has, in fact, shown that the food which is administered by the members of a colony to the young larvae determines, at more than one stage of their development, their transformation into kings or queens, or soldiers or workers as the case may be, and the value of these researches is increased by the observations which he has made on the instincts of the different forms, showing that they do not in early life differ from one another in this respect, and are all equally endowed with the potentiality of the same instincts. These do not, however, all become developed and cultivated in all alike, but become specialised, as does the physical structure in the full-grown forms.

A very different piece of work, but having a no less important bearing on the theory of organic evolution, is that on the Geptocephali. These strange, colourless, transparent, thin-bodied creatures, with blood destitute of red corpuscles, had been regarded as a special family of fishes, but have been proved by Grassi’s patient and longcontinued labours to be larval forms of the various Mursenoids. The most astonishing case is that of the Common Eel, Anguilla vulgaris, the development of which had been a mystery since the days of Aristotle. It had been long known that large eels pass from rivers into the sea at certain seasons, and that diminutive young eels, called in this country Elvers, ascend the rivers in enormous numbers. But, although the species is very widely distributed, no one in any country had been able to discover how the elvers were produced. Grassi has shown that, large as the eels are that pass into the sea, they are not pei’fectly developed fish, but only attain maturity in the depths of the