546 SUMMARY OF CURRENT RESEARCHES RELATING TO 



muscle-cells, malpighian vessels, etc. It is also possible that they do 

 not appear simultaneously, but in a definite order of succession. The 

 definite order of the histolytic processes points to this. 



Eyes of Diptera.* — Jan Zavrel has investigated the eyes of various 

 larvfe and pupte of Diptera. He finds that in Sayomyia, Chironomidfe, 

 Simuliuni, there occur during development either two or three pairs of 

 eye primordia. Since this phenomenon is repeated not only in single 

 species but in whole and different famiUes, it admits not of a ' biological 

 but of a morphological interpretation. The facts support the theory of 

 Radl of the duplicity or triplicity of the lateral Arthropod eyes. 



Chermes of Colorado Conifers.f — C. P. Gillette gives an account of 

 the members of this genus found on Conifers in Colorado. Some of the 

 species are decidedly injurious to pines and spruces when used as shade 

 trees in parks or private grounds. The males, in the United States at 

 least, are unknown. Six species or varieties are dealt with, most of 

 which are new, and much information is supplied regarding habits, host- 

 plants, injuries and natural enemies, and life-histories. 



Larvae of South African Anophelina.J — E. Hill and L. G. Haydon 

 discuss the value of larval characters in species diagnosis, and find that 

 in the case of nine species collected in Natal, the sum total of the 

 characters is sufficiently pronounced to establish identity. They did not 

 find any characters of specific value other than those set forth by 

 Christophers and Stephens — viz. antennae, frontal or clypeal hairs, 

 thorax, palmate hairs. They describe the nine species identified and 

 give notes on individual variations, habitat, seasonal occurrence, and 

 relation to malaria. 



Lead-Gnawing Insect.§ — The " Enghsh Mechanic " records a case 

 of a bug (so-called) which is the cause of considerable damage to 

 the lead covering of underground telephone cables in Chicago stock- 

 yards. 



Distribution of Injurious Insects by Artificial Means.|| — F. T. 

 Theobald recounts the various ways in which injurious insects are dis- 

 tributed by the agency of man, and indicates the origin, means of 

 dissemination, and present distribution of a number of important insects 

 attacking fruit-trees in orchards and gardens, and also of various animal 

 pests. Dispersal as an accompaniment of human intercourse has taken 

 place mostly from north and south towards the equator. Many 

 temperate-climate insects live and flourish in sub-tropical and tropical 

 climates, but the reverse only applies within certain narrow limits 

 according to each species. It is unlikely that many tropical pests would 

 persist in the warmer parts of Europe ; an instance of such, however, is 

 the yellow-fever mosquito, which has evidently spread from the central 

 American states, and can live as far north and south of the equator as 

 48°. A sub-tropical species which is spreading into temperate regions 



* Zool. Anzeig., xxxi. (1907) pp. 247-55 (13 figs.). 



t Proc. Acad. Nat. Sci. Philadelphia, lix. (1907) pp. 3-22 (11 pis.). 



X Annals Natal Govt. Museum, i. No. 2 (1907) pp. 111-57 (12 pis.). 



§ English Mechanic and World of Science, No. 2201, Ixxxv. (1907) p. 897. 



II Science Progress, No. 1 (1906) pp. 58-72. 



