22 IN SECT A. 



objections, however, were raised against the method em- 

 ployed by Plateau, and he afterward devised a new method 

 carrying on extensive and more conclusive researches. i 

 At the same time he made comparative investigations with 

 the vision of vertebrates, and as a result proved that while 

 the latter had clear vision, easily and skilfully directing 

 their movements, the insects "acted in all cases as if they 

 had a veil before their eye^" ^ and could not perceive sharp 

 images of any immovable object. 



Notthaft ^ gives a number of figures showing how im- 

 perfecdy these animals distinguish the forms of objects. 



Between the compound eyes is the first pair of ap- 

 pendages, the jointed antennae (PL I., Fig. 3, at; Figs. 

 1,2). These are articulated to the head in such a way 

 that they move freely in any direction. The observa- 

 tions heretofore made upon these organs indicate that 

 they have very important functions, and a direct con- 

 nection with the brain, which cannot be severed in 

 most insects without serious injury to the animal. The 

 exact nature of these functions, however, has not been 

 satisfactorily determined. In some a special sense 

 seems to reside in the antennce, which is neither ex- 

 clusively a sense of touch, hearing, taste, nor smell. 



The experiments of Trouvelot^ on Limenitis Disippus, 

 Godt., and of Packard^ on Colias, Pier is, and others, show 



1 Recherchcs experimenfales sur la Vision chcz les Arthro- 

 ppdcs. Parties I.-V., Bruxelles, 1887-88. 



'^ See Butterflies of the Eastern U.S. and Canada, Scudder, 

 pp. 1670-71. 



^ Abhandhingen senckenberg. naturforsch. Gesellschaft. 

 Frankfurt, XII., 188 1. For a further discussion of the subject, 

 see The Cockroach, Miall and Denny, pp. 98-109. 



* American N'attiralist, Vol. XL, April, 1877. 



5 American Naturalist, Vol. XL, July, 1877. 



