52 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Nerve-Cells of Cockroach.* — Rolfe Floyd has used various methods 

 in studying the nerve-cells in the thoracic ganglia of Pcriphnvta orien- 

 talis, and finds that they possess no evident cell-walls, that their nuclei, 

 though exhibiting a reticulum, with enlarged nodal points and irregular 

 amorphous deposits, after must fixing reagents, are homogeneous in 

 appearance in the fresh condition, and after fixation in formalin vapour. 

 They contain nucleoli and an entire nuclear membrane ; the cytoplasm 

 contains a fine anastomosing reticulum, whose interstices show no 

 structure or staining affinities in the fresh condition. There are, how- 

 ever, one or more substances, presumably existing in the cytolymph in 

 the normal living cell, that may change in character and form deposits 

 upon the cyto-reticulum under the influence of fixing reagents, post- 

 mortem changes, arsenical poisoning, etc. The deposit, or rather the 

 material from which it is derived, is reduced by prolonged nervous 

 activity ; it in some way represents the potential energy of the cell ; it 

 seems to correspond with the chromophilic substance of the nerve-cells 

 of higher animals. 



Australian Thysanoptera.t. — TV. TV. Froggatt explains that the three 

 species of Idolothrips described by Halliday, viz. 7". spectrum, I. marginata, 

 and /. lacertina, are the two sexes, and a smaller and more variable form 

 of the male, all of the same species. The characters of egg, larva 

 {several stages), pupa and imago are given, together with notes on habits 

 of this form, I. spectrum. 



Entomological Notes.J — N. Cholodkovsky gives an account of the 

 histology of the yellow spots and the knob-shaped hairs of the cater- 

 pillar of Acronycta aim. Each hair is connected with two cells, one of 

 which, the trichogen, is plainly glandular in character. Notes are also 

 given on the dark blue neck-stripes of the caterpillar of Gastropaclm 

 pini, and on the wax-making glands of Chermes. 



Stridulation in Ranatra fusca.§ — J. R. De La Torre Bueno has 

 repeatedly observed that this member of the Hemiptera cryptocerata pro- 

 duces a chirping noise when taken out of the water. This is due to the 

 movement of the anterior coxae in the deep and elongated joint-surfaces 

 on the lower surface of the prothorax. 



Classification of Hexapoda.|| — A. Handlirsch proposes a new 

 classification of the Insecta, claiming that the groups proposed are not 

 artificial and arbitrary, based on external similarity, but phylogenetic 

 concepts. Thus his sub-classes are not co-extensive with the old Orders. 

 The following are his Classes : — 



I. Collembola (Lubbock), 2 Orders. 

 II. Campodeoidea (= Archinsecta Haeckel), 2 Orders. 

 III. Thysanura (Latr.), 2 Orders. 

 IV. Pterygogenea (Brauer), 11 Sub-classes, embracing 28 Orders. 



* Mark Anuiv. Vol.. 1903, pp. 339-58 (4 pis.). 



J - Proc. Linn. Soc. New South Wales (1901) pp. 54-7 (1 pi.). 



t Zool. Jahrb., xix. (11)04) pp. 55i-(30 (1 pi.). 



§ Canad. Kntomol.,xxxv.(1903) pp. 235-7. See Zool. Zentralbl. xi. (1901) p. 592. 



j| Zool. Anzeig., xxvii. (1904) pp. 733-59. 



