458 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Inbreeding of Dilina tilise.* — Alfred Kolisko has continued in- 

 breeding; experiments for several years with this Lepidopterous species. 

 It occurs in two main forms— a typical green form and a brown variety. 

 The brown form is relatively constant, varying a little between a lighter 

 and a darker reddish brown. The green form is extremely variable — 

 from whitish green to dark olive green, and sometimes shows areas of 

 brownish yellow. The greens produce greens and the browns browns. 

 Crossing green and brown, results in some of the progeny being green 

 and others being brown, but there is no blending of the two colours. 

 Numerous varieties that have been named arise as degenerate changes 

 in the course of inbreeding. 



Ovaries of Pine Beetle.j — E. Knoche seeks to correlate a sort of 

 dimorphism in Myelophus piniperda with its two modes of nutrition. 

 It may eat under the bark of trees or in the young shoots. In the 

 former case, the diet stimulates the sex-cells ; there is premature 

 senescence and weakening of the organism as a whole. In the other 

 case, the soma is stimulated and the development of the gonads is 

 slowed. Degenerative appearances in the ovary may be induced experi- 

 mentally by starving the beetles. 



Development of Donacia crassipes.J— Jan Hirschler gives a de- 

 tailed account of the development of this beetle. He deals with the 

 differentiation of the blastomeres on to establishment of the ectoderm 

 and the genital primordia ; the segmentation of the blastoderm and 

 the appearance of the appendages ; the formation of the enveloping 

 membranes and the differentiation of the so-called lower layer ; the 

 differentiation of the mesoderm, and the development of the alimentary 

 canal and the blood-cells ; the establishment of the vascular system, 

 tracheal system, etc. ; and the history of the genital primordia. 



Eyes of Diptera.§ — W. Wesche has studied a large number. The 

 highly chitinised plate, pierced with circular apertures for the lenses, is 

 the most primitive form. In higher forms the facets begin to be 

 hexagonal and there is much less opaque chitin, until, finally, in 

 specialised insects like the blow-fly (Calliphora), the opaque structure 

 has quite disappeared, permitting all rays of light to enter the eye. 

 The author has paid particular attention to the differences between the 

 eyes of males and females. The greater amount of eye-surface in the 

 male probably gives room for a greater number of facets, and thus 

 the male is better able to find his mate. This extreme development of 

 the eyes is well seen in Pipunculidge, where the head of the male is 

 almost entirely occupied by the compound eyes. But there are other 

 sexual characters — the eyes of the -male are often nearer one another ; 

 the eye of the male may be divided into an upper and a lower part, and 

 it may be more pubescent. 



* Verb. Zool. Bot. Ges. Wien, lviii. (1908) pp. 244-58. 



t Verh. Deutsch. Zool. Ges., 1908, pp. 224-30. 



% Zeitschr. wiss. Zool., xcii. (1909) pp. 027-744 (6 pis. and 15 figs.). 



§ Joum. Quekett Micr. Club, 1909, pp. 367-84 (1 pi.). 



