ZOOLOGY AND BOTANY, MICHOSCGPY, ETC. 295 



Light Reactions of Vanessa antiopa.* — William L. Dolly, jun.,. 

 has studied the reactions to light in this mourning-cloak butterfly. 

 The facts that the butterfly can orient with but one eye functional, 

 that in a beam of light " circus movements " become less frequent and 

 the angle of deflection decreases with experience, that the degree of 

 deflection is no greater in a light of high intensity than it is in a light 

 of low intensity, that the butterfly can turn under certain conditions- 

 toward either side when only one eye is illuminated, and that these 

 insects can in the process of orientation turn either toward the functional 

 or the blinded eye, indicate that orientation in this case is not wholly 

 dependent upon the relative intensity of light on the two eyes. The 

 facts also show that the path in the nervous system along which the 

 impulses travel is not permanently fixed. The nature of the orienting, 

 stimulns must be left at present an open question. 



Luminescence of Fire-flies.f — E. Newton Harvey has experimented 

 with the American Photuris pennsylvanica and Photiaus pyralis, the 

 Japanese Luciola vittkoUis and L.parva, and the West Indian " Cucullo," 

 Pyrophorus noctilucans and P. havaniensis, all essentially the same a& 

 regards luminescence. A light-producing substance or photogenin is 

 found in the luminous gland-cells ; a light-assisting substance or photo- 

 phelein is distributed throughoat the body. 



Photophelein is much more stable than photogenin ; it may be kept 

 for over seventy days ; it dialyses readily through collodion ; it is not 

 readily affected by ether and benzol. Photogenin, on the other hand, dis- 

 appears in less than five hours at 25° C, is quickly destroyed by ether- 

 benzol, and chloroform, and will not dialyse readily, if at all. 



Study of a Species of Bracon.J— James W. Munro has studied a 

 species of an Ichneumon fly, Bracoii, which is parasitic in the Pine 

 Weevil, Hylohkis ahietis, the most formidable forest-pest in Britain. 

 The female lays eight to twenty-two eggs in the weevil-grub. The 

 eggs are long, spindle-shaped, white, glistening, 0*9 mm. in length 

 by 0'15 mm. in median diameter. They hatch in two to four days. 

 Five larval stages are described. When the parasites are full fed their 

 host is reduced to an empty sac, and the parasites now fill the cavity 

 in the bark previously occupied by their host. It is here they spin their 

 cocoons. The adults are very active and strongly attracted to light. 



■ Bionomics of Lice.§ — A. Bacot has made a study of Pediculus 

 humanus {vestimenti) and P. capitis. The former is larger, more robust^ 

 less active, with larger and more numerous eggs. Cross-pairing is easily 

 effected, and the offspring are fertile inter se ; hybrid strains were 

 maintained till the third filial generation, but there remained no reason, 

 judging from breeding results, why such strains should not be continued 

 indefinitely. 



* Journ. Exper. Zool., xx. (1916) pp. 357-420 (21 figs.). 



t Amer. Journ. Physiology, xlii. (1917) pp. 342-8. 



i Proc. Roy. Soc. Edinburgh, xxxvi. (1915-16) pp. 313-38 (2 pis.). 



§ Parasitology, ix. (1917) pp. 228-58. 



