ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 165 



some. Decisive evidence as to sex-chrotnosomes can only be obtained 

 by tracing their individual history and by accurate correlation of the 

 chromosome-numbers in the spermatogonial and spermatocyte divisions. 



Comparison of Nervous Systems of Insects.* — K. F. Kiihnle 

 gives an account of the brain, cerebral nerves, and head-glands of the 

 common earwig (Forficula auricularia) and compares these with what 

 he finds in a bug {Tomocerus flavescens), a termite (Eutermes peruana.*), 

 and a walking-stick insect (Dixippus morosus). He gives a careful 

 analysis of the proto-, deutero-, and trito-cerebrum, and the nerves 

 arising from these parts. 



New Order of Insects. | — F. Silvestri describes three species of an 

 interesting new genus, Zorotypus, from the Gold Coast, Ceylon, and 

 Java, and proposes a new order Zoraptera for their reception. The 

 insects are minute, terrestrial, wingless, and agile ; they live among 

 rotting vegetable debris, and seem to catch mites and the like. The 

 mandibles are strong biting organs ; the antennas are short and monili- 

 form ; there are conical single-jointed cerci ; the thorax is relatively 

 long ; the abdomen has 10 segments, 8 stigmata, and 2 ganglia. 



Tracheal Capillaries among Fibres of Wing-muscles. % — J- 

 Athanasiu and J. Dragoiu describe the tracheoles or fine capillary 

 branches of the tracheae among the fibres of the wing -muscles in Hydro- 

 philus. Penetrating below the sarcolemma the branches divide into 

 a large number of capillaries which lie between the columns, some 

 longitudinally, some transversely. In a longitudinal section it is seen 

 that the space between two muscle columns is occupied by a tracheal 

 capillary with an approximate diameter of 0*001 mm. The transverse 

 capillaries are seen as minute dark circles. The ramification is extra- 

 ordinarily rich, and it is a very interesting point that it is not seen at 

 all in the muscles of the legs. 



Skin and Glands of Dytiscus marginalis.§— Alois Casper describes 

 the cuticle, hypodermis (single-layered), and the basal membrane. The 

 cuticle is formed in part by secretion, in part by a direct change of the 

 cell-plasma of the hypodermic cells. The cuticle is made up of many 

 lamellae and beams, and has a complex structure. The insertion of 

 muscles is effected by an epithelial tendon (modified cells of the hypo- 

 dermis). 



There are varnishing unicellular glands, modified epidermic cells. 

 Packets of such cells occur which have a specialized function, e.g. at 

 the genital apparatus. Or a more compact packet is formed, and the 

 chitinous tubules open on a common cribellum. This occurs on the 

 jaws. A third type of packet occurs, with looser vesicular cells. 



Invagination and the differentiation of a canal lead on to more 

 complicated glands — offensive, pseudoacinous, and pygidial. These are 



* Jen. Zeitschr. Naturw., 1. (1913) pp. 147-276 (5 pis. and 39 figs.). 



t Boll. Lab. Zool. Scuola Agricoltura Portici, vii. (1913) pp. 193-209 (13 figs ) 



t Comptes Rendus, clvii. (1913) pp. 1168-71 (2 figs.). 



§ Zeitschr. wiss. Zbol., cvii. (1913) pp. 387-508 (44 figs.). 



