500 THE SENSES AND SENSORY ORGANS. 
Lubbock [195] has shown, perhaps, that the range of luminous 
vibrations visible to insects differs somewhat from that of those 
discerned by man, and suggests the same with regard to sound 
vibrations. It is very possible that such is the case, but this is 
no evidence that they possess any kind of sensation entirely 
different from our own. As the proof of any such sensation is 
impossible, it is useless to discuss it. 
Sporadic Sensory Organs.—It is now well known that sensory 
organs of great complexity occur in the most unexpected posi- 
tions in many Invertebrates; not only eyes, but auditory organs, 
even in closely-allied forms, are found in very various parts of 
the body. For example, amongst the saltatorial Orthoptera, the 
Acrididz have complex organs of hearing on the first abdominal 
segment, whilst the Grillida have similar organs on the anterior 
tibia. In the decapod Crustacea ears have been found on the 
antennules, whilst Mysis has auditory organs in the tail. Graber 
has found chordotonal organs in various parts of the thorax and 
abdomen and in their appendages in both larval and perfect 
insects. In the Diptera, the halteres present characters which 
have led many to ascribe an auditory function to them, and 
they are probably correct in this view; lastly, in many Diptera 
there is a complex organ in the meso-thorax closely connected 
in its nerve-supply with that of the halteres, which I regard 
as probably auditory. 
Bibliography : 
196. SERRES, MARCEL DE, ‘Mémoire sur les Yeux composée et sur les 
Yeux lisses des Insectes.’ 8vo., Montpellier, 1813. Also published in 
Berlin in German, in 1826. 
197, MULLER, JOHANNES, ‘Zur Vergleichenden Physiologie des Gesichts- 
sinnes des Menschen und der Thiere, nebst einem Versuch, iiber die 
Bewegungen der Augen und iiber den menschlichen Blick.’ 8vo., 
Leipzig, 1826. 
198. MULLER, JOHANNES, ‘ Ueber die Augen des Maikafers.’ Archiv. f. 
Anat. u. Physiol. (Meckel’s), 1829. 
199. DuGis, A., ‘Observations sur la Structure de lzil composé des 
Insectes,’ Ann. des Sc. Nat., tom. xx., 1830. 
200. WAGNER, R., ‘Einige Bemerkungen iiber den Bau der Zusammen- 
gesetzen Augen der Insecten.’ Archiv. f. Naturgeschichte (Wiey- 
mann’s), Jahrg. 1, Bd. i., 1835. 
