Literary Notices. 291 



is asserted above but not demonstratetl, thouirh the course of the mes- 

 encephabc root of the trigeminus would support such a view. This 

 view hardly furnishes an explanation of the peculiar position of Reiss- 

 ner's fiber. o. s. s. 



Parker, G. H. The riiototropism of the Mourning-Cloak Butterfly Vane.ssa 

 antiopa Linn. Art. XXIII, pp. 453-569, pi. 33. 



V. a/ifiopa orients itself in sunlight with its head away from the 

 sun and so that a straight stick held vertically at an appropriate point 

 casts a shadow that falls exactly on the length of the butterfly's body. 

 So invariably is the head directed away from the sun that when rest- 

 ing on tree trunks the butterflies face toward the foot of the tree. If 

 the surface on which it rests '"is perpendicular to the sun's rays the in- 

 sect settles without reference'to the direction of the rays." Neverthe- 

 less, " V. antiopa creeps and flies toward a source of light, that is, it is 

 positively phototropic in its locomotor responses." This positive pho- 

 totropism of flight or other locomotion and negative phototropism in 

 rest are otherwise not unknown. 



Now the author finds that the resting animal keeps its wings spread 

 in sunlight and that the position of negative orientation most fully ex- 

 poses the wings to light and makes the insect conspicuous. The habit 

 is therefore probably a means of bringing males and females together. 

 Furthermore, it is the eyes which govern the reaction, since any part 

 of the body except the head may be shaded without disturbing the 

 animal, which, however, flies away if the head is shaded. This ob- 

 servation is confirmed by various experiments on animals of which the 

 eyes have been painted over. If one eye is blackened, that side of 

 the insect keeps in motion and the body moves "in a circle, with the 

 unaffected eye toward the center." If both eyes are blackened, the 

 insect does not come to rest, but flies upward, showing a negative geo- 

 tropism which is readily verified on normal individuals in a perfectly 

 dark room. 



V. antiopa discriminates little, if at all, between different intensi- 

 ties, much more between lights of diff'erent area. It "remains in flight 

 near the ground" and, although in locomotion positively photropic, does 

 not fly upward toward the sun, "because it reacts positively to large 

 patches of bright sunlight" rather than to small ones, even though the 

 latter, as in the case of the sun, may be much more intense." These 

 reactions are probably based on retinal images which the insect gets. 

 If the sun is clouded over the animals fold their wings. 



The "heat-rays" of sunlight seem not to influence the reactions, but 

 an actual change of temperature of the air is effective. A marked de- 



