36 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



system of insects. The present part forms fascicles 16 and 17 of a 

 monograph on the economic importance, development, habits, and 

 structure of insects. It is profusely illustrated, and contains exhaustive 

 bibliographies. 



Thoracic Segments in Hexapoda and Chilopoda.*^ — L. B. Walton 

 has investigated the subject of the dorso-lateral longitudinal muscles in 

 the Geophilidffi, and finds that their arrangement corresponds to the 

 division of the segment into an anterior and posterior somite. This, 

 together with the presence of homologous areas in ScoJopendrella, 

 Camjwdea, Forficula, etc., presents a strong case for regarding the 

 segment in the Hexapoda and Chilopoda as composed of two somites. 

 There is evidence for considering that not only is the thorax in Hexa- 

 poda composed of six somites, but that each typical segment in the 

 Hexapoda and Chilopoda (Crustacea and Arachnida ?) is composed of 

 two coalesced somites. 



Wax-Glands of Honey-Bee.f — L. Arnhart finds that in bees which 

 are actively secreting wax, the cells of the wax-gland are surrounded by 

 intercellular spaces full of air and communicating with adjacent tracheae. 

 Dreyling noticed these intermediate spaces, but thought that they con- 

 tained secretion. They contain air only, and their occurrence shows 

 that the production of wax is associated with a strong oxidation. 



Coiling of the Aorta in the Bee.J — L. Arnhart calls attention to 

 the observation of Pissarev, that the aorta, after leaving the heart, but 

 before passing out of the abdomen, exhibits eighteen coils. He in- 

 terprets this as an arrangement hindering the back-flow of the blood, 

 talang the place of aortic valves. The mechanism of the valves in the 

 heart itself is also discussed. 



Spermatogenesis of Hive-Bee.§ — L. Doncaster finds that the 

 nucleus of the primary spermatocyte resolves itself into eight dyads, 

 instead of the usual tetrads ; there is only one complete maturation 

 division, which separates the halves of the dyads, so that eight single 

 chromosomes pass to each pole. He confirms the suggestion of Giglio-Tos, 

 that in the spermatogenesis there is no reduction in the ordinary sense, 

 and that the failm-e of the first maturation division is due to the fact 

 that the primitive germ-cells of the drone contain the reduced number 

 of chromosomes, as might be supposed, if the drone is produced from an 

 unfertilised esfor. 



"&&• 



Proventriculus and Gizzard of Wood-cutting Bee.|l — L. Bordas gives 

 a detailed account of the minute structm'e of these parts. The gizzard 

 not only triturates the food, but acts as a regulating filter, and prevents 

 (by means of a valve) the material from passing upwards during the 

 peristaltic movements of the mid-gut. 



* Science, n.s., xvii. (1903) pp. 485-6. 



t Zool. Anzeig., xxx. (1906) pp. 719-21 (1 fig.). 



X Tom. cit., pp. 721-2. 



§ Anat. Anzeig., xxix. (1906) pp. 490-1 (5 figs.). 



jl Trav. Scient. Univ. Rennes, iv. (1905) pp. 303-19 (9 figs.). 



