448 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the life-histories, and the ceeology. Thus there is a discussion of the 

 formation of galls and an account of their minute structure. Among 

 the other subjects treated of we may mention the parthenogenesis of 

 Tenthredinidse. 



Acridiidae of British India.* — The late W. F. Kirby left a not 

 quite completed account of the Locusts or Short-horned Grasshoppers 

 of British India, which has been prepared for publication by C. 0. 

 Waterhouse. Members of the family of Acridiidse may be generally 

 recognized at a glance by the short antennae and the three-jointed tarsi, 

 and thus distinguished from the other Leaping Orthoptera — the Gryllidas 

 or Crickets, and the Phasgonuridse or Long-horned Grasshoppers 

 called (often improperly) Locustidre. The memoir deals with no fewer 

 than 329 species. 



Pupation of Holometabolic Insects.f — E. Poyarkoff publishes a 

 study of the evolution of insect-metamorphosis with a view to establishing 

 a theory of the pupation of holometabolic insects. He deals with the 

 biological significance of the moult in general, and of the nymphal and 

 imaginal moults in particular ; the different periods in insect-metamor- 

 phosis ; the mode of appearance and characters of the primitive nymph ; 

 the establishment of the period of nymphal inactivity in the development- 

 cycle of holometabolic insects ; the cessation of external alimentation, 

 the retreat of the nymph into a shelter ; the exuvial glands ; the general 

 course of the development of the tissues during metamorphosis ; the 

 organs of the nymph ; the biogenetic law and the metamorphosis of 

 insects ; the phyletic significance of the pupa stage ; and the primitive 

 number of imaginal stages. Very generally stated, the author's theory 

 is that primitive hemimetabolic insects had only a single imaginal stage 

 — the word stage being carefully distinguished from " period " — and 

 that this single stage in hemimetabolic insects is in holometabolic insects 

 subdivided, by the addition of a new imaginal moult, into two, a nymphal 

 stage and an imaginal stage. 



Reduction of Wings in Orthoptera. — R. Puschnig $ discusses this 

 subject, with especial reference to the conclusions of H. Karny who 

 supports Dollo's thesis of "irreversibility." According to this thesis 

 there is no reversibility in a phylogenetic sequence ; organs which have 

 reached a certain stage in a given direction cannot return to a previous 

 stage. The discussion deals very largely with secondarily macropterous 

 forms which occur in series with reduced or absent wings. Karny 

 emphasizes the change in the structure and venation of the wings ; 

 Puschnig emphasizes the apparent return to a large-winged ancestral 

 type. Karny § replies to Puschnig's points. 



* Fauna of British India. Orthoptera (AcridiidsB) (1914) ix and 276 pp. 

 (140 figs.). 



t Arch. Zool. Exper., li. (1914) pp. 221-65. 



X Zool. Jahrb. Abth. Allg. Zool., xxxiv. (1914) pp. 515-32. 



§ Zool. Jahrb. Abth. Allg. Zool., xxxiv. (1914) pp. 532-42. 



