ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 23 L 



wipe it off their tongues. The author came to the conclusion that 

 at least the Hymenoptera and Diptera are provided with a gustatory 

 sense. The tongue and the neighbouring mouth-parts are fully de- 

 scribed, and the conclusion is come to that the pits or goblets on the 

 base of the tongue, and on the lower side of the maxilla, are the 

 end-organs of the gustatory apparatus. The nerve ends on the 

 surface, and is thus accessible to direct chemical stimulation, the parts 

 can be washed with saliva, while the supply of hooks and setae partly 

 retains the saliva for cleansing purposes, and partly defends the 

 delicate ending of the nerves. The terminal setas on the top of the 

 tongue may also be regarded as gustatory organs ; this is indicated 

 by the part played by the tip of the tongue in the early stages of the 

 ingestion of food, by the observation of the mode of feeding adopted 

 by these insects, and by the structure of this region. The terminal 

 sensory hairs do not project freely, so there is no reason to suppose 

 that they are tactile organs ; they are rather carefully protected, both 

 by the hooks and setfe of the tongue, and by the thick circlet of 

 supporting hairs. In ants the goblets at the tip of the tongue are 

 formed exactly on the plan of those which are found at its base. 



The author's observations lead him to deny a gustatory function 

 to the nerve-end-organs which are found in other parts of the mouth, 

 for they all fail in the preliminary condition of being able to 

 come into direct contact with the food ; all the numerous pits which 

 are found elsewhere have very fine pale hairs, none of which are 

 provided with a groove or perforated at their extremity. 



Mid-gut of Insects and Regeneration of Epithelium.* — Dr. J. 

 Frenzel follows up his recent research | on the histology of the 

 crustacean gut, by a detailed study of the mid-gut (" Mitteldarm ") of 

 insects, and of epithelial regeneration there and elsewhere. His 

 material consisted of sixty different species selected from all the seven 

 great groups of insects ; for hardening purposes, he found that a 

 mixture of alcoholic solution of sublimate and nitric acid gave the 

 most satisfactory results. The memoir is introduced by a general 

 anatomical description of the alimentary canal, and especially of the 

 mid-gut in its various modifications. 



General histology. — (a) The innermost layer of the mid-gut is 

 composed of an epithelium of large, almost cubical cells, which passes 

 out into the diverticula if such exist, and which may, though fre- 

 quently quite equal and uniform, exhibit numerous regular internal 

 villi, or sometimes pads. (&) Eound the epithelium lies a sheath of 

 connective tissue, in the form of a loose meshwork of fibres and 

 nuclei, filling up the spaces between the villi, or between the 

 epithelium and the musculature, or else represented by a distinct 

 basement membrane, also without recognizable cellular composition, 

 (c) Further out lie the muscular layers, circular internally, and 

 longitudinal externally. Their main effect is the shortening of the 

 gut ; a narrowing of the lumen can also be effected. The muscles are 



* Arch. f. Mikr. Anat., sxvi. (1885) pp. 229-306 (3 pis.). 

 t See thia Journal, v. (1885) p. 994. 



