166 SUMMARY OF CURRENT RESEARCHES RELATING TO 



described in detail. The offensive glands repel larger enemies. The 

 secretion of the other two types serves to close up the air-chambers 

 under the elytra and between pro- and mesotliorax. The imago shows 

 a distinctly segmental arrangement of its larger glands. The glandular 

 cells have a vesicular nucleus, a reticulate plasma, an internal vesicle, 

 and a chitinous tubule. Secretion is preceded by an increase of 

 chromatin by the nucleolus ; the secreted product appears in the 

 plasma, collects around the vesicle, passes along fine plasmic threads 

 through the membrane of the internal vesicle, and thence osmoticaliy 

 through the wall of the chitinous tubule. During each secretory period 

 the chromatin of the nucleus is temporarily exhausted. 



Odoriferous Organs of Female Lepidoptera.* — Ernst Urbahn has 

 made a detailed study of these organs, which may occur in the vicinity 

 of the external genitalia or elsewhere. Illig and Freiling have dis- 

 tinguished (a) protrusible scent-areas {Phalera, Pygsera) • (b) evaginated 

 scent-rings (Pterostoma, Cucullia, Golocasia) ; (c) the dorsal scent-fold 

 of Lymantriidas ; (d) intersegmental scent-sacs {Hi/pocrita, Callimorpha, 

 Saturnia, Aglia, Argynnis) ; (e) the glandula? odoriferse of species of 

 A rgynnis ; and (/) the ventral tufts of Agrotis fimbria. All scent-organs 

 that are restricted to the females are abdominal. They always lie at the 

 end of the abdomen and are either tufts or intersegmental folds, sacs, 

 and the like. The folds and sacs arise from an intersegmental fold, 

 usually between 8 and 9, which has become glandular. There are large 

 glandular cells with large nuclei, and a plasma with numerous secretion- 

 vacuoles. 



Trophi of Leaf-Miners. f — Ivar Tragardh describes the larvaa of a 

 series of Lepidopterous leaf-miners. He has been able to follow the 

 whole of the interesting transformation from the so-called " flattened 

 type" to the cylindrical type. A pronounced dimorphism in the 

 mouth-parts of the younger and the later instars occurs in those forms 

 where there are two well-defined, and in some respects entirely different 

 periods in the life-history of the larva. The difference depends on the 

 two methods of feeding and mining. The one method is to cut a thin 

 horizontal slice in the parenchyma and suck the sap ; the other method 

 is to eat mouthful after mouthful of the parenchyma, excavating a mine 

 without wounding the epidermis. The relation of the mouth-parts to 

 the sap-feeding and tissue-feeding is illustrated in detail. 



Larva of Egle spreta.J — Ivar Tragardh describes the eggs and 

 larvae of Egle (Anthomyia) spreta, which he found on Epichloe typhina, 

 a fungus attacking grasses (Phleum pratense and DactyUs glomerata). 

 Three instars which, differ greatly, are described. When they hatch the 

 larvae use the egg-shell as a cover, but soon form a thin oblong-oval 

 tube of faecal or fungoid matter. From this cover the larva makes ex- 

 cursions into the fungus, devouring it, and "leaving broad winding 

 streets." As it grows it adds to its tube, which becomes as broad as the 



* Jen. Zeitschr. Naturw., 1. (1913) pp. 277-358 (2 pis. and 26 figs.), 

 t Arkiv Zool., viii. (1913) No. 9, pp. 1-48 (67 figs.). 

 X Arkiv Zool., viii. (1913) No. 5, pp. 1-16 (1 pi.). 



