618 sr.M.MARY OF CURRENT RESEARCHES RELATING TO 



Fatty Body during Metamorphosis.* — A. Hufnagel describes the 

 changes exhibited by the fatty body in Hijponomeuta padclla, e.g., that 

 some cells arc destroyed by phagocytes, while the majority persist and 

 exhibit :t remarkable expulsion of chromatin from the nucleus into the 

 cytoplasm — an " epuration chromatique." 



Flying Apparatus of Blow-fly .f — Wolfgang Ritter gives a thorough 

 account of the structural arrangements involved in the flight of Calli- 

 phora vomitoria, and describes their manner of working. The constituents 

 of the wing-joint are three, the processus pterales thoracis, the pteralia, 

 and the processus pterales alae. The flexibility of the material permits 

 some relative movement of different parts of the same piece of chitin. 

 It is all very different from a Vertebrate's joint. 



The indirect muscles produce the elevation and depression of the 

 wings ; the direct muscles change the shape and position of the wings 

 and the course they travel in a beat ; the direct muscles are probably 

 also steerers ; the downstroke of the wing is forward relative to the 

 insect, and directed, in ordinary forward flight, downward and forward 

 also relative to the surrounding air ; it produces an elevation of the 

 insect's body, which overcomes gravity but retards the forward move- 

 ment. During the horizontal movement of the wings, when depressed 

 forward and also during the upstroke, the wings act as gliders, counteract 

 gravity and retard horizontal advance, or vice versa. The fly descending 

 glides forward, or ascending loses its horizontal velocity. The torsion of 

 the wing attains its maximum at the end of the downstroke, because its 

 anal portion lags behind the anterior part during the downstroke in con- 

 sequence of its flexibility and the resistance of the air. Toward the end 

 of the upstroke the torsion is at its minimum. The folds of the surface 

 and the hairiness of the wing affect its mechanical effect on the air. The 

 numerous small folds of the anal portion of the wing, which is poor in 

 veins, serve to strengthen it. 



Oriental Species of Stomoxys.J — Sophia L. M. Summers finds that 

 the characters most to be relied on are the width of the frons in relation 

 to the width of the head, the width of the median line on the thorax, and 

 the colour of the legs. The abdominal markings can be relied on to a 

 certain extent only. Ten species are dealt with, including Stomoxys 

 pratti sp. n. 



] Cave Diptera. § — M. Bezzi has found in grottos representatives of 

 twenty-six families of Diptera, but the majority of these are only occa- 

 sional visitors. The family of Heleonryzidae is most characteristic. No 

 form without wings has been found ; no blind form has been found, 

 though some Heleomyzidee show a reduction of eyes. Some forms show 

 an elongation of antennas ; some show an expansion of the abdomen. 

 N( > clear case of reduction of pigment has been found ; but the author 

 is strongly of opinion there are genuine cavernicolous Diptera. 



* C.R. Soc. Biol., lxx. (1911) pp. 635-7. 



t Smithsonian Misc. Coll., lvi. (1911) No. 12, pp. 1-76 (19 pis.). 



X Ann. Nat. Hist., viii. (1911) pp. 235-40 (5 figs.). 



§ Arch. Zool. Exper., viii. (1911) pp. 1-87 (23 figs.). 



