394 Dr. Sharp's account of recent experiments 



The first chapter is of an introductory nature, being 

 devoted to a review of the actual condition of anatomical 

 and physiological knowledge as to simple eyes, and 

 speaks in very favourable terms of Patten's recent 

 researches. 



In the second chapter he passes to an account of his 

 own experiments on Myriopods, commencing with 

 Lithohius forficatus. By placing specimens in a box 

 lighted in certain parts but obscure in others he found 

 that this species is very sensitive to light ; but this 

 sensitiveness he considers is not necessarily due to the 

 eyes, for other Myriopods, such as Geophiliis and 

 Cryptops, which are destitute of eyes, display almost as 

 great a sensitiveness to light, and this he considers is 

 due to a dermatoptic faculty. After this he proceeded 

 to test the capacity for perceiving objects by putting the 

 Lithohius in a maze or labyrinth formed by placing 

 pieces of wood, card, or other such materials in a circle 

 interrupted by gaps, and then forming other circles 

 outside this (see PL XIII., fig. 1). Any creature possessed 

 of the sense of sight would escape from such a labyrinth 

 by passing between the gaps by means of a slightly 

 zigzag course, while an animal not able to see might be 

 expected to run against the pieces forming the inter- 

 rupted walls of the labyrinth. The Lithohius, on being 

 placed in the centre of the maze, walks straight up to 

 the obstacles till it comes against them with its antennae, 

 and then turns to one side, passes through a gap, and 

 repeats this process with the next series of obstacles, 

 and so on until it escapes, the rate of progress being 

 about one inch per second. The eyes of the Lithohius 

 were then covered with impervious black dye, and it was 

 found that the insects then escaped in an exactly similar 

 manner, and quite as rapidly as those whose eyes were 

 not covered. Experiment was then made with speci- 

 mens of Lithohius from which the antennte had l)een 

 removed ; these proceeded in a similar manner to those 

 that were intact, but, not being warned by their antennae 

 of the proximity of the objects, they actually ran against 

 these, then turning to one side, knocked against another 

 object, and so on (PL XIII., fig. 1, track c). 



Similar experiments were then made with Cryptops, a 

 naturally blind Myriopod, and as a result of a com- 

 parison, Professor Plateau concludes that in LitlioKiL^ 



