THE PRESIDENT'S ADDRESS. 381 



who has spent years in the research, and who published an almost 

 exhaustive treatise in the Vienna " Denkschriften " in 1876 on 

 these organs in the Orthoptera. 



The auditory organs in insects are clearly related to the tracheal 

 system, and it is a remarkable fact that their locality is very 

 variable ; thus in the locust and the green grasshoppers they are 

 on the anterior tibiae ; in some field crickets ( Acridioidce) they are 

 on the first abdominal segment near the back. I may announce that 

 I have discovered a most perfect ear, similar in all respects to that 

 of these field crickets, in the fly, except that it is on the mesothorax. 

 I trust soon to publish a fall account of this organ. There is also 

 a drum similar to the drum of the cicads and the field crickets 

 (Grylloidoe ) which in these insects produces the sounds they emit; 

 this drum is in close proximity to the ear. 



The sensory nerve terminals of the auditory nerves in the fly 

 are identical with the so-called chordotonal organs which serve 

 this function in the Orthoptera. Whilst speaking of Dr. Graber's 

 discoveries in relation to the auditory organ 1 take the opportunity 

 of mentioning that he has published a little book on insects — " Die 

 Insekten," Munich, 1877 — which, for those who read German, is far 

 the best and most complete account of the anatomy and development 

 of insects ever published in a popular form, and that the work gives 

 a complete resume, of all the more important recent discoveries. 

 It is a charming little work on insect anatomy and development, 

 quite up to the date of its publication. 



It is only recently that the intimate structure of the central 

 nervous system has received any attention. Till lately it was con- 

 sidered that the ganglia of the thorax and of the head have a 

 similar value and structure, and insects were spoken of as " homo- 

 gangliate." 



Dietl in 1876 first examined the brain in serial sections, and 

 investigated the nature of certain convoluted pedunculated organs 

 which Dujardin had called attention to, in bees and ants, a quarter 

 of a century before. Flogel took up the subject about the same 

 time, and invented a nomenclature for the parts, which he described 

 accurately. I believe, with certain modifications, Flogel's nomen- 

 clature is very unlikely to be superseded. Flogel's paper appeared 

 in 1877, and was immediately followed by a paper from the pen of 

 Emil Berger, less satisfactory, however, than Flogel's, and a year 

 later by E. T. Newton's papers on the brain of the cockroach, 



