ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC. 293 



statement has been added of the more serious deficiencies in our know- 

 ledge of this interesting family. 



History of Polar Bodies in Drone-Ova.*— A. Petrunkewitsch has 

 shown that while the polar bodies of the fertilised ova of the bee come 

 to nothing, the state of affairs in the unfertilised ova (drone-ova) is very 

 different. The second polar body coalesces with the internal half of 

 the first, and thus gives rise to the so-called "directive-copulation- 

 nucleus " with the normal number (1G) of chromosomes. The nucleus 

 soon forms the " directive-copulation-spindle," and divides into 2, 4, 8 

 cells with double nuclei. What becomes of these direct derivatives of 

 the polar bodies ? After prolonged investigation Petrunkewitsch has 

 satisfied himself that they give rise to the primitive sex-cells of the male. 

 The difference between the origin of the primitive genital cells in the 

 two sexes is striking. 



Development of Wings in Beetles.! — W. L. Tower has studied 

 this in a variety of forms. He finds that the wings and the spiracles 

 arise in homologous positions upon the sides of the segments as deter- 

 mined by the attachment of homodynamous muscles. He believes that 

 the hind wings are derived from the degenerate spiracle disc of the 

 metathorax. In the elytra the case is different. Whether in the migra- 

 tion of the mesothoracic stigma to its larval position only the opening 

 migrates and the disc remains behind, or whether both the spiracular 

 disc and opening are moved forward, remains undecided. The author's 

 evidence points strongly to the view that it is the spiracular opening 

 alone which migrates, and that the spiracular disc remains behind to 

 form the primordium of the elytron. At present the evidence seems 

 strongly in favour of Verson's (1890) view that the wings of Coleoptera 

 and Lepidoptera are derived from the rudiments of the mesothoracic 

 and metathoracic spiracles. The evidence is positively opposed to the 

 theory that the wings originate as dorsal backward prolongations of the 

 tergum, and the theory that wings are derived from structures like 

 tracheal gills lacks substantial support. 



Screw- Worms in St. Lucia. :f — St. George Gray discusses the occur- 

 rence of this parasite in man, where, as in cattle, &c. it is sometimes 

 fatal. The screw-worm is the larva of a small fly — Ghrysomyia {Comp- 

 somyia) macellaria Fabr. The eggs are laid in wounds and in openings 

 of the body, e.g. mouth and nostrils ; they hatch in 1-9 hours. The 

 larv?e are rather slender, whitish, active maggots, with twelve segments, 

 each bearing a ring of minute spines or bristles, suggesting the appear- 

 ance of a screw ; they burrow into the tissues, devouring even bones, 

 and may penetrate into the cranial cavity ; they mature in a week or 

 less, and a pupa stage of 9-12 days is passed in the ground, in crevices, 

 in bedding, &c. The author recommends the destruction of filth, 

 carcasses, &c, the careful covering of wounds, the use of mosquito 

 netting or wire gauze in sleeping rooms, and the protection of the 

 nostrils in places where the flies are common. 



* Stool. Jalirb., xvii. (1903) pp. 481-51*; (3 pis.). 



t Tom. cit, pp. 517-72 (7 pis. and 8 figs.). 



\ Brit. M. d. Journ., No. 2204, March 28, 1903, pp. 724-5. 



