cl GENERAL SUMMARY OF SCIENTIFIC AND 



a simple lining of epithelial cells. This fluid has no anal- 

 ogy with the gastric fluid of vertebrate animals. Its func- 

 tion differs according to the group to which the insect be- 

 longs. In the carnivorous beetles it makes an emulsion of 

 the greasy matters ; in the Hydrophilid beetles it continues 

 the conversion of starch into glycose, begun in the oesopha- 

 gus. In the caterpillars of the butterflies and moths it de- 

 termines a production of glycose, and makes an emulsion of 

 greasy matters ; and in the grasshoppers no sugar is formed 

 in the intestine, as this material is produced and absorbed in 

 the (Esophagus (jabot). The intestine proper is only a fcecal 

 reservoir. The urinary or Malpighian tubes sometimes se- 

 crete calculi. No bile has been found in the secretions of 

 these tubes. A point of great importance is touched upon 

 by the author, namely, the passage of the chyle from the 

 stomach to the blood. It is well known that there are in 

 Articulates no lacteals as in Vertebrates to effect this process. 

 Plateau states that the products of digestion pass through 

 the walls of the digestive canal by an osmotic action, and di- 

 rectly mingle with the blood. 



At the last meeting of the American National Academy 

 of Sciences, Professor A.M. Mayer exhibited an experimental 

 confirmation of the theorem of Fourier, as applied by him in 

 his propositions relating to the nature of a simple sound, 

 and to the analysis by the ear of a composite sound into its 

 elementary pendulum-vibrations; and showed experiments 

 elucidating the hypothesis of audition of Helmholtz. Plac- 

 ing a male mosquito under the microscope, and sounding 

 various notes of tuning-forks in the rano;e of a sound given 

 by a female mosquito, the various fibres of the antennae of 

 the male mosquito vibrated sympathetically to these sounds. 

 The longest fibres vibrated sympathetically to the grave 

 notes, and the short fibres vibrated sympathetically to the 

 higher notes. The fact that the nocturnal insects have high- 

 ly organized antenna?, while the diurnal ones have not, and 

 also the fact that the anatomy of these parts of insects shows 

 a well developed nervous organization, lead to the highly 

 probable inference that Professor Mayer has here given facts 

 which form the first sure basis of reasoning in reference to 

 the nature of the auditory apparatus of insects. 



The external breathing apparatus of aquatic insects, called 



