1-18 histitute of France. 



edifice, tried to ascertain how far these opcr:'.ticns arc connected 

 with the instinct of the cater:viliar, and may be varied by it ac- 

 cording to cirt'imstance'5. A caterpillar which he took away 

 from the construction it was making, began it ngain so long as 

 there remained any silky matter. If he placed it on a con- 

 struction made by another, it continued it in general from the 

 point where the other hail left off; but if the latter was far ad- 

 vanced, it preferred beginning de 7iovo. The butterfly which 

 issues from the caterpillar seems to be the phalceim dcrkella 

 of Linnaeus, and one of its enemies is the khneiimon ramicor7iis. 



Our colleague M. de la Billardisre has observed a remarkable 

 fact relative to the instinct of wild bees, or those large velvet 

 bees which form their nests under the turf, in stones, &;c. He found 

 towards the end of autumn in a nest of the species called opis 

 sylvarvvi, by Kirby, an old female and a working bee whose 

 wings were glued together with brown wax, so as to prevent 

 them from flying; and he thinks this was a precaution taken by 

 the other bees to constrain these two individuals to remain in 

 the nest, and to take care of the lar\£e which next year were 

 to replenish the population of the colony. 



M. Olivier, men.iber of the Class, has made on the insects 

 Whicli are enemies to corn, experiments ^vhich belong equally to 

 agriculture and to zoology : he has hitherto treated of only those 

 species which attrck corn in the ear. M. Olivier describes nine 

 of those, all belonging to the order of two-winged insects ; but he 

 describes at the same time three oth.er insects, enemies of the 

 above, and which of course stop their mischief. 



One of the most important questions in the anatomy of insects 

 concerns the use of a large A'essel which the whole of this class 

 carry along the back, and which undergoes movements of dila- 

 tation and contraction like those of the heart and arteries. 

 Malpighi and Swammerdam have given it the name of heart; but 

 it is evident from the observations ofLvonnet and several others, 

 that no branches issue from it; and M. Cuvier seems to have 

 proved by many experiments, that insects have no circulation. 

 M. Marcel de Serres has taken up this subject again : he ascer- 

 tained by innumerable observations made upon the largest in- 

 sects in the south of France, and assisted by the most delicate in- 

 struments, that the dorsal vessel gives out no r.amifications ; that 

 there exists in the body no other contractile vessel, and in ge- 

 neral no system of blood-vessels. Insects from which the dor- 

 sal vessel is removed live for several hours, whilst scorpions and 

 spiders, which have a real heart, perish speedily if it be destroyed. 

 The contractions of the dorsal vessel are chiefly owing to the 

 muscles of the back placed along its sides, but the tracheae and 

 the nerves exert a sensible influence on them. The humour 



which 



