582 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Colour-pattern of Wings of Diptera.* — Professor J. F. van 

 Bemmelen has studied this in species of Hsematopoda, Pmcilostola, 

 Sciomyza, Traginops, Tephritis, and other genera, and finds confirmation 

 of his view that there is a regular and simple but complete original 

 colour-design common to all Diptera. It is possible to find a connexion 

 between patterns of widely different appearance ; to derive one pattern 

 from another ; to find along different lines of evolution a recurrence of 

 the same sequence of patterns. As in Hepialids, " the motives and 

 patterns of the colour-design are older than the genera and families 

 which display them." 



Effects of Light on Rate of Locomotion in Vanessa antiope.j — 

 W. L. Dolley has made experiments to test the effects of intermittent 

 light and continuous light of different illuminations on the rate of 

 movement in V. antiope, with special reference to Loeb's " continuous 

 action theory" of orientation. The experiments did not bear out 

 Loeb's theory, for the butterfly did not move faster in strong light than 

 in weak, but rather moved faster in weak than in strong light if the 

 difference in degree of illumination was sufficiently great. This 

 corroborates the conclusions reached by the author in an earlier paper. 

 In intermittent light of a frequency of interruption of ten and sixteen 

 per second Vanessa moves faster than it does in continuous light. This 

 supports the contention that in this butterfly orientation in light is due 

 to the time rate of change of intensity. 



Setal Pattern of Caterpillars.^ — A. Schierbeek continues his study 

 of the arrangement of bristles and homologous structures in caterpillars. 

 He showed that the abdominal pattern was more primitive than the 

 thoracic, that a primitive type and three derivative types could be 

 distinguished, that stripes were evolved later than spots, and so on. 



He goes on to express his agreement with Boas as to the meta- 

 thoracic stigma having moved forward on to the intersegmental 

 membrane between meta- and mesothorax, and as to the so-called 

 prothoracic stigma being really that of the mesothorax. In accordance 

 with Poulton and Spuler, he has been able to trace an eleventh 

 abdominal segment in certain caterpillars during their first instar, as in 

 Hepialus hecta, FhaUra hucephala, Sphinx ligustri, and Pieris hrassicse. 



Schierbeek conceives of the primitive chrysahs as being provided 

 with considerable power of movement and with a setal pattern. The 

 pupa represents an immobilized subimaginal stage. As the pupal 

 pattern generally agrees with that of the first larval instar, but only 

 with that of the full-grown larva in cases in which the latter has 

 retained the primitive design, the conclusion is drawn that the pupal 

 stages as well as the first larval instar bear a primitive character in 

 distinction to the later larval instars, which represent secondarily 

 introduced phases of development. 



* Proc. Akad. Amsterdam, lix. (1917) Nos. 9-10, pp. 1141-56 (10 figs.). 



t Journ. Exper. Zool., xxiii. (1917) pp. 507-18. 



\ Proc. Acad. Amsterdam, xix. (1917) Nos. 9-10, pp. 1156-61. 



