492 



Marvels of the Universe 



THE TRACING OF A MAGNETIC STORM. 



Automatic register of the movements of two of the magnetic needles at Greenwich Observatory during the ' magnetic storm" 

 of February 13-14. 1892. The beginning of the trace shows the usual character of the magnetic movements, but at 5h. 30m. a.m. 

 on February 1 3 a sudden vibration was shown by the needles in all the magnetic observatories of the world, after which their 

 oscillations became very violent and rapid. 



but the range of colour is considerable, even apparently in the same individual and in normal 

 health. Those from which my photographs have been taken (with the kind permission of Mr. 

 Carl Hagenbeck), and which are exhibited at the Insectorium in the Tierpark at Stellingen, are not 

 merely emerald-green or grass-green ; but some of them are yellow or reddish-yellow, especially 

 when in contact with slightly fading oak-leaves. Others, again, are bright sulphur-yellow or russet- 

 green. The resemblance in general tone to the foliage of the oak (on which these insects were 

 feeding at the time of my visit) was so extraordinary that, although I possess very good sight, I 

 thought at first that the Curator was merely holding up for my inspection bunches of oak-leaves ; 

 and it was only when I saw the insects begin to move that I realized they were there. The like- 

 ness to vegetation begins with the very extrusion of the egg from the body of the female, the 

 eggs being of large size and enclosed in still larger capsules exactly resembling ribbed seeds. So 

 close is the resemblance that it might even deceive the eye of a botanist, who would believe that he 

 had picked up a seed-capsule enclosing a seed. These eggs fall to the ground and in due time 

 hatch out into minute, reddish-coloured, active young Leaf Insects, not unlike baby locusts in 

 appearance. They at once proceed to crawl up the stems of plants, and soon after they have 

 begun eating the leaves they become green in colour. They do not at first possess to the full 

 the remarkable developments of the front or hind wings (according to sex), or the leaf -like 

 expansions of the legs. But these soon appear, and until they have come to perfection the insect 

 is protected from observation by the artfulness of its attitudes and its " colourable imitations " of 

 leaf or twig. 



The food of these Leaf Insects is purely vegetable. They eat nothing but leaves, and can actually 

 be deceived into nibbling each other in the belief that they are eating leaves ! But it is said that 

 they do not inflict mortal injuries on their companions, as they merely nibble away the appendages 

 to the limbs, which soon grow again. In fact, by their rapid assimilation of vegetable matter they 

 really become, in course of time — as the natives of the countries in which they exist believe 

 them to be — walking leaves, their very colouring matter being hardly more than the assimilated 

 chlorophyll of the plants on which they live. 



