158 THE POPULAR SCIENCE MONTHLY. 



count fifty species in Europe. More than a hundred have been found 

 by Ileer, of Zurich, and Mayr, of Vienna, in the cantons of Oeningen 

 and Radoboj alone; several seem identical with existing species. Most 

 of them have wings ; these are males and females. Workers are rare ; 

 and that is explained by the nature of the rock, deposited at the bot- 

 tom of still waters. The winged insects fell into it by thousands; the 

 workers, more lowly in existence, attached to earth, have left fewer 

 victims in the streams that preserve the record of that age. For the 

 same reason, those sepulchres, so rich in species, teach us nothing of 

 the habits or abodes of the ants of that time. What we do know is, 

 that there were also plant-lice in the country, and that the larvae of 

 phryganes made for themselves even then, as they do now, those cases 

 in which they live, and which they carry about everywhere with them. 

 Some of these have been found at Oeningen. We have butterflies' 

 wings of that era with their marks, if not with their coloring. Who 

 knows whether we shall not some day discover a wasps'-nest dropped 

 from a bough, and a trifle less regular than those of to-day ? Even 

 were it just as perfect, that would in nowise weaken the hypothesis of 

 progressive development in the instinct by which it was built. Should 

 we not have, beyond the Jurassic epoch, an enormous past, beside 

 which the actual age now of the deposits of Oeningen and Radoboj is, 

 perhaps, like a day or an hour in the history of man ? 



The grand result which the introduction of Darwin's ideas into bio- 

 logical science has had is, beyond question, to have transformed a sub- 

 ject hitherto deemed unapproachable and insolvable into a question of 

 development that may be attacked by our investigations. Instinct, 

 like the outward forms of animals, has always been made dependent 

 on those first causes too high for man to raise his look to them. The 

 observations of the English naturalist have brought the problem upon 

 new ground ; his logic, his science, have forced the world to accept at 

 last the ideas formerly defended by Cuvier's opponents, by Lamarck 

 and Geoffroy Saint-Hilaire. The doctrine of the immutability of ani- 

 mal forms has had its time, and that of the invariability of instinct is 

 falling into ruin. Darwin proves, in fact, that it suffices to admit the 

 principle of intelligence, which no one now denies to animals, and then 

 the twofold influence of habit and hereditary tendency, and last that 

 law, stated by himself, of absorption of the poorly-endowed races by 

 these better endowed, to reach the conclusion that the finely-perfected 

 instinct of the bee or the ant is nothing more than a purely natural 

 phenomenon, a necessary consequence of life. The most complex in- 

 stinct is merely an hereditary accumulation of very simple habits, of 

 which the first source was always in the spontaneous intelligence of 

 the individual. Instinct, then, including that of neuter animals, may 

 be defined, "a group of habits, slowly acquired, and fixed by inheri- 

 tance." Then it appears to us as independent, in some degree, of the 

 forms of the animal ; the variations it presents find their explanation ; 



