254 THE SCHOOL OF REAUMUR 



Caterpillars ^ 



The methodical account of caterpillars describes the 

 variety of external features which they present. How 

 dreary we find such a collection of obscure differences 

 when handled by a dull man ! E^aumur however 

 knows how to enliven his account by graphic touches. 

 When he has to speak of the food-plants of caterpillars, 

 he remarks that some feed with impunity upon acrid 

 leaves ; this leads him to mention one of the hawk- 

 moths, whose larva refuses all food except the leaves of 

 spurge. E^aumur put some of the milky juice of the 

 spurge upon his own tongue, and at first noticed no 

 distinct sensation. But in the course of an hour or so 

 his mouth seemed on fire, and repeated rinsing with 

 water could not allay the pain. The larva of the hawk- 

 moth however was ready to drink several drops in 

 succession of this caustic juice, and experienced no ill 

 effects. Again, he tells us that many kinds of cater- 

 pillars which he attempted to rear perished because 

 provision had not been made to satisfy their special 

 instincts. Some are in the habit of hiding underground 

 by day, and must therefore be supplied with loose earth. 

 Reaumur made this discovery by noticing that some 

 caterpillars of the cabbage moth (Mamestra brassicse) 

 and the common dagger-moth (Acronycta Psi), which 

 he had supplied with young cabbage plants, were not 

 to be found upon them next day. A fresh supply of 

 caterpillars was procured, and these also disappeared, 

 but the leaves had been much gnawed, so that E^aumur 

 began to suspect that the caterpillars had not gone far 

 away. On searching the earth in the pots, they were 

 found buried, but at night a visit paid by candle-light 



^Vol. I, M(5m. ii-iv. 



