574 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Gynandromorphs of Drosophila ampelophila.* — F. N. Duncan 

 has made a microscopic study of five gynandromorphs of Drosophila 

 ampelophila in order to determine whether the gonads corresponded to 

 the secondary sex characters expressed by the somatoplasm. He finds 

 that the gonads of lateral gynandromorphs do not follow the separation 

 of the somatic cells into a male and female side, but are always either 

 male or female on both sides. 



Apodous Insect Larvae. f — I). Keilin refers to Dollo's X conception 

 of " the irreversibility of evolution " — that an organism cannot return 

 even partially to a state previously realized in the series of its ancestors — 

 and discusses in the light of it the disappearance of thoracic appendages 

 in Dipterous larva?. Reduction of limbs occurs in many larvae that are 

 parasitic in animals (e.g. in some Hymenoptera and Strepsiptera), or 

 parasitic in plants (e.g. in some Hymenoptera and some Coleoptera and 

 Lepidoptera, or living on food prepared by the adult, or burrowing in 

 dead wood. The reduction is always secondary and usually adaptive. 

 In some Dipterous larvse, which are all apodous, the life is free, but 

 this is a secondary return to freedom, a re-adaptation, and it has not 

 been associated with a re-development of appendages. There are often 

 ventral projections with hooks ; the mandibles may aid in locomotion, 

 as in Mycetobia ; there may be various sorts of attaching organs, as in 

 forms living in streams ; the larvae of Phora use their mouth as a leech 

 does ; and other cases are noticed. But the point is, that although 

 there has been a return from a parasitic or xylophagous mode of life to 

 freedom, there is not any trace of a reappearance of appendages. This 

 illustrates Dollo's idea of irreversibility. 



Structure of Glow-worm. § — E. Bugnion discusses some points in 

 regard to the structure of Lampyris noctiluca, especially in reference to 

 the mouth-parts. The adults take almost no food, the larvae devour 

 small snails. Bugnion seems to believe in the paralyzing and liquefying 

 effect of a poisonous secretion injected into the victims. The mandibles 

 of the larva are, as Fabre said, perforated by a fine canal, and in Lam- 

 prorhiza delarouzei the same is true. In the abdomen, at the level of the 

 anterior end of the stomach, there are two acinous glands which prob- 

 ably secrete the toxic and liquefying fluid. The duct probably opens at 

 the base of the mandibles. The mandibular canals of the glow-worm 

 differ from those of the larval ant-lion and Dytiscus in having no 

 communication with the mouth. The liquefied food is taken in by the 

 mouth, and the absorption is probably aided by the capillary action of 

 numerous hairs about the mouth. There is a muscular gizzard at the 

 entrance to the stomach. The mandibles of the adult are not traversed 

 by a canal, and their tip seems to be incapable of piercing or tearing. 

 Bugnion's results should be compared with those recently stated by Miss 

 Kathleen Haddon,|| with which they are not altogether in agreement. 



* Amer. Nat., xlix. (1915) pp. 455-6. 

 t Bull. Soc. Zool. Prance, xl. (1915) pp. 38-43, 



X Bull. Soc. Beige Geol., vii. (1893) pp. 164-6, and Mem. Soc. Beige Geol., 

 xxiii. (1909). 



§ Proc.-Verb. Soc. Vaud. Sci. Nat., 1915, pp. 92-4, in Bull. Soc. Vaud., i. (1915). 

 || See this Journal, 1915, p. 252. 



