ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 363 



case the fibrillse are united into bundles of various sizes by a cement- 

 ing substance, in which the nuclei lie either both in the interior and 

 upon the surface of the bundle {Hydrophilus, Dytiscus), or upon the 

 surface only (flies). The bundles are held together by tracheae, and 

 sometimes also by fat-cells. In the cement, further, are always found 

 distinct particles (Aubert's masse grumeleuse interfibrillaire), which do 

 not occur in the other muscles. The fibres are composed of fibrillse, 

 and have nuclei either upon the surface (Cicada) or in the middle 

 (Lihellula). In some insects the fibrillte are arranged as in a folded 

 lamella, the leaves of the folds running out from the centre of the 

 fibre towards the surface, seen in cross-sections. The nerve-fibres 

 terminate in motor plates (probably several for each fibre), consisting 

 of a granular basal substance, in which are imbedded the ramifications 

 of the axis-cylinder. The wing-muscles are more readily dissociated 

 into fibrillae than those of the rest of the body, from which they are 

 further differentiated by the absence of a true earcolemma. 



Flight of Insects.* — M. Amans thinks that in the theories of 

 artificial wings, propounded by Marey and Pettigrew, both observers 

 have failed to see that the base of the wing is formed of two planes 

 set at an obtuse angle in such a way that, when the wing is descending, 

 the posterior plane presents its concavity to the column of air struck. 

 The author has made some anatomical observations on ^sclina, Siren, 

 and Locusta, which seem to confirm his view. 



Locomotion of Insects on Vertical Glass Surfaces.! — H. Dewitz 

 supports the explanation already advanced by Blackwall of this pheno- 

 menon, viz. that a glutinous liquid is exuded from the apices of hairs 

 which surround the lobes of the feet. He resorts to direct observation of 

 the living insect, fixing it feet uppermost to a glass slide which is placed 

 under the Microscope. By this means the ends of the hairs surround- 

 ing the lobes of the feet are seen to emit a transparent substance by 

 which the foot adheres to the glass ; if the foot is then drawn away, 

 drops are seen to be left on the glass, corresponding in position to the 

 hairs of the foot-lobes. In cases where there are no hairs, as in the 

 bugs, the adhesive material proceeds directly from pores in the foot. 

 Many larvae (e. g. Muscidce, the alder-leaf beetle, and the saltatory 

 Dipterous larvae) use a similar substance in their movements, pro- 

 bably also half the total sum of perfect insects, including most Diptera 

 and Hemiptera, many Hymenoptera and Ooleoptera, and probably 

 those Orthoptera which neither leap nor fly. 



The same author t has examined the structure of the foot of a 

 beetle, Telephorus disjpar, and other insects with the same object. The 

 hairs on the foot run out to sharp points, below which are placed the 

 openings of the canals. The glands are chiefly flask -shaped unicellu- 

 lar organs, lying in the hypodermis of the chitinous coat ; each opens 

 into one of the hairs ; they are each invested by a structureless tunica 

 propria, and they contain granular protoplasm, a nucleus placed at 



* Comptes Kendus, xcvi. (1883) p. 1072. 



t SB. Gea. Naturforsch. Freunde (Berlin), 1882, pp. 5-7. * 



X Tom. cit., pp. 109-13. 



