Scudder.] 316 November 6, 



tweeu the sides of a leaf were caused by the greater force 

 of the wave in its ascent or descent ; such peculiarities as 

 have been pointed out between the leaves of the hop-horn- 

 beam or the elm, existed, therefore, in the earliest formation 

 of the leaf" while yet connected with the axis by a broad 

 base, and before any constriction for the petiole had taken 

 place. Professor Agassiz thought that the inverse relation of 

 corresponding parts on opposite sides of a line, was better 

 expressed by the word antitropy — proposed by Schimper and 

 Braun — than by the word symmetry, which is employed in 

 very different senses. 



Mr. S. H. Scudder repeated his remarks on the stridulation 

 of grassho])pers, given at the last meeting of the entomological 

 section. He also illustrated on the black-board the structure 

 of the stridulating organs, showing the distinction between 

 the singing males and the voiceless females in the same 

 sj)ecies. 



Professor Agassiz inquired whether the size of the cavities 

 of the tubes which formed the framework of the wings had 

 anything to do with the pitch of the notes produced by dif- 

 ferent insects. He had observed great variety of size in the 

 tubes which he had examined. 



In reply, Mr. Scudder referred to a statement of Professor 

 Agassiz that every vocal family of animals uttered its dis- 

 tinctive cry. In the same way every fimily of grasshoppers 

 could be recognized by the peculiar pitch of its note, even 

 when the species was unknown; and since the pitch was 

 common to all members, great and small, and the diameter 

 of the tubes bore usually a regular proportion to the size of 

 the insect, the pitch could not depend upon the size of the 

 tubes alone. It was probably more closely connected with 

 the delicate vibrating membrane of the wing, for, in crickets, 

 where the pitch is highest, the stridulating surface is much 

 larger than in any other family of Orthoptera, Avhile the note 

 is lowest in the jumping grasshoppers, where the vibrating 

 space is broken up by many ci'oss veins. 



In fulfillment of his promise at the previous meeting, Pro- 

 fessor Agassiz brought forward the results of an examination 



