146 THE entomologist's record. 



a premise not even mentioned in the original account of the 

 swarm. In fact, one is forced to the conclusion that Piepers 

 came to the consideration of this part of the subject with pre- 

 conceived notions, and, instead of attempting to explain the facts, 

 is inclined to make the facts fit his assumptions, and the value 

 of this contribution to an interesting subject is thus largely rendered 

 nugatory. The " proof " he offers that the flights are the result of 

 individual action is that, in 1883, whilst the great flight of CatapKilia 

 crocalc in Java was in progress (it lasted some Aveeks, and the larvae 

 and pupae, as well as imagines, of C. crocalc were in great numbers) he 

 observed that the newly-emerged insects did not remain for a time 

 where they were born, but, as soon as their wings were perfected, 

 they flew oft' en coijay/e with the others. He states that he then col- 

 lected some larvae, reared them, and, one morning, when a dozen 

 imagines emerged from the pupae, took the glass case in which they 

 were to some distance from the house, and placed the case on the 

 grass, in the sun, and where the inmates might see the flight of their 

 cimfrcrea throughout the day ; after a short time he opened the case, 

 the butterflies came out and he watched some of them fly away like 

 the others that were passing, directly in a straight line and in the 

 same direction, flying over the house (which was in the line of flight) with- 

 out passing it on one side, whilst others, also apparently well developed, 

 flew feebly into the trees, their flight showing that they were too weak to 

 undertake a long flight, the well developed ones flying ofi', the weaker 

 ones staying behind, and on this experiment he bases the conclusion 

 already formulated, and which he states thus: " C'etait done bien 

 comme jel'avais presume ; tout papillon nouvellement eclos ressentait 

 aussitot le besoin d'aller voler de la maniere decrite. C'est done ainsi 

 que se constituent ces vols, qui par la multitude des insectes, qui en 

 font partie, nous semblent etre des rassemblements, un acte produit 

 par entente commune, mais qui ne sont en eft'et qui le resultat d'une 

 quantite d'actes tout individuels sans coherence, auxquels chaque 

 insecte est pousse par son instinct sans se soucier des autres " (p. 225). 

 There is, he adds, no general assembly from the commencement, nor 

 a common point of departure, each butterfly commences its flight 

 where it finds itself the moment it becomes an imago, and it is to be 

 presumed that the finish will be the same, that each butterfly will assume 

 at a given moment the ordinary manner of life for the species. A com- 

 prehensive conclusion one feels on such a small array of experiment. As to 

 when the individuals will leave the flight and renew the ordinary conditions 

 of life, Piepers suggests that it is determined by sexual conditions. He 

 notes that the butterflies fly straight on without being attracted by the 

 flowers that are in their course ; he observes, however, that a small group 

 occasionally detaches itself from the flight, making for the large trees, 

 and that he believes each group to consist of a female with some males in 

 attendance, and that this was the prelude to copulation. M. Westpalm 

 van Hoorn had already stated that he believed that butterflies ceased to 

 take part in the flight after copulation ; Hepp also remarked that small 

 groups quitted the flight, and rested some moments in the trees. Piepers 

 concludes that such cases represent a pairing, the paired couple being left 

 behind unnoticed, the unsuccessful males in a short time pursuing their 

 flight. He assumes, as we have already noted, that after copulation the 

 paired imagines remain in the vicinity where pairing has taken place, and 



