ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 651 



The method also permits a very easy adjustment of lights in their 

 intensity, by raising or lowering the wicks, and thus allows the 

 observer to test the strength of mere illumination against attractive- 

 ness of colour as a hue for the insects. The planting of the lights 

 seems important. I started by placing them in a row at long dis- 

 tances from each other. The defect of this arrangement appeared to 

 be that the brilliancy of the first light, encountered by the insects 

 coming upon it from its side or portion of the row, interfered with 

 tlie visitor's freedom of choice as between that colour and another 

 when the light from the others reached it in a dim and imperfect 

 manner. The lanterns were then arranged in a square (four colours), 

 whose dimensions were determined by the intensity of the several 

 lights. The distance between the lanterns was such as to allow the 

 limital circle of illumination of each at first to touch, and subsequently 

 to intersect those of its neighbours. This distance was reduced until 

 the separation between the lanterns was less than the radius of the 

 circle of light which each threw around itself, the lights being of 

 equal intensity. This proved unsatisfactory, and having devised no 

 means of exhibiting a number of coloured lights so that the chances 

 were equalized completely for insects coming from all sides, to choose 

 according to any constitutional preference for one colour over another, 

 I used only two colours at a time. The arrangement might be found 

 useful to place four lanterns in two pairs, each pair of one colour, and 

 in a diamond pattern, so that each colour appears equally prominent, 

 no matter from what side the dazzled insect may approach the group. 

 The apparent necessity for allowing the insect to choose instantly 

 between the colours before it reaches either arises from the infatuation 

 produced in the insects by the light, which, once reached, seems to 

 obliterate all capability in the creature to free itself from its entice- 

 ment, except in an irregular and accidental manner. My experiments 

 proved nothing except the absence of any marked preferences for 

 certain colours over others, and the almost invariably greater charm 

 exerted by the white lanterns, which., on account of their translucency, 

 appeared more brilliant than the coloured lamps." 



j8. Myriopoda. 



Scolopendrella.* — J. Wood-Mason has some observations on this 

 remarkable Myriopod, which he thinks to be more nearly related to 

 the Chilognatha, though in the form of the body it resembles the 

 Chilopoda. It would appear to be the descendant of a group of 

 Myriopods, which have given rise to the Campodese, Thysanura, 

 and CoUembola. The form in question presents two of the most 

 remarkable features of Peripatus — two-clawed feet and segmental 

 openings; these last are the apertures which Eyder described as 

 stigmata. The tracheal tubes themselves are all devoid from their 

 very origin of the spiral thickenings in the walls, which are so cha- 

 racteristic of the trachea of insects ; in the body the author has not 

 been able to make out any tracheae, except those which are meta- 



* Ann. and Mag. Nat. Hist., xii. (1883) pp. 53-63. 



