34 THE BUTTERFLIES OF NEW ENGLAND. 



In Newport's observations (Phil, trans., 1834) on the changes in the 

 nervons cord of Aglais vu'ticae (86:2-12), he shows a more considerable 

 change between forty-eight and fifty-eight honrs than perhaps between any 

 others of the stages he has drawn and described, which are successively 

 (after the pupal state is assumed) 1, 13, 18, 24, 36, 48, and 58 hours. 

 .Vccording to his account the second and third (original) ganglia at this 

 period "approach and coalesce, and the double ganglion thus formed is 

 only separated from the larger thoracic mass, composed of the fourth and 

 fifth ganglia, and part of the sixth, by very short but much enlarged cords." 

 ^^s the figures given by him do not in themselves show how this amalga- 

 mation of the second and third ganglia is affected, I examined the nervous 

 cord of Hamadryas, 48, 51 and 55 hours after pupation, with the follow- 

 ing results : The pupa of 48 hours age differs from that of Aglais only in 

 the separation of the fourth ganglion from the united fifth and sixth ; very 

 short and broad ribbons connected them, but they were unmistakably sepa- 

 rated by half the width of the fourth ganglion ; while the third and fourth 

 ganglia were separated by about the diameter of the latter ganglion, At 

 51 hours the condition was more as represented by Newport at 48 hours in 

 Aglais, the fourth, fifth and sixth ganglia being completely amalgamated 

 into a single long ovate mass, while the third, though clearly distinct from 

 the mass behind it, was separated from it by only less than half its own 

 diameter, very short, stout ribbons uniting the two ; it was also of the same 

 size as at 48 hours, and the second ganglion, instead of travelling toward 

 the third, as Newport asserts, retained very nearly or quite its own place, 

 but was reduced in size, being gradually absorbed in place by the cord.* 

 This absorption was entirely effected at 55 hours, as was also the complete 

 amalo'amation of the third ganglion with the mass behind it. The second 

 ganglion then is not amalgamated with the third, but disappears in place — 

 a point quite in keeping with the lessening importance, but continued in- 

 tegrity, of the prothorax. 



In the chrysalis of the European Mancii)ium brassicae, however, in which 

 these changes, in the wintering pupa, take place far more slowly, Her- 

 old figures the nervous cord as if the second ganglion did not disappear 

 in place but united with the third to form a common mass from which 

 the lateral cords of both the ganglia are represented as derived. 



Reproductive organs. Tlie only noticeable difference between the 

 male organs of the young pupa and of the caterpillar is in tlie complete 

 union of the glands of the two sides into a spherical body, and in the tortuous 

 path now taken by the threads that unite it to a sac lying beneath the ex- 

 tremity of the alimentary canal. Its furtlier development is entirely in 

 these two latter parts ; the threads merely grow in diameter and somewhat 



*Brautlt asserts, from observations on this of ganglia takes place only by amalgamation, 

 and other species, that reduction in the number never by absorption (Hor. soc. ent. Ross., xv.) . 



