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THE BRITISH NATURALIST. 



[May 



younger naturalists will take up the study, for it is a very wide and 

 open field, and one that will well repay a little attention. 



It is my purpose to write a few notes on some new and little-known 

 larvae of the Diptera. These two-winged flies have, most of them, 

 been well known from the days of Aristotle, who first classified them. 

 They have accompanied man in all his peregrinations, and have been a 

 considerable annoyance to him and his domestic animals, etc., through 

 all the centuries, and yet it is only quite recently the life histories of the 

 Gnat, the Blow-fly, the Daddy Long-legs or Crane fly, the Wheat midge 

 or Hessian fly, the Bot fly, and the Gall fly, and others, have been 

 fully worked out ; and the large amount of work yet to be done opens 

 an exceedingly wide field for investigation. It is only by enrolling 

 those interested in the evolution and development of insect life that any 

 progress can be made, and I do not know that any subject offers the 

 earnest student a nobler aim than does the study and investigation of 

 this branch of natural history. 



We well remember in our boyish days pondering over the 

 phenomenon of living matter constantly undergoing change, as seen in 

 the pupa or chrysalis of the Moth or Butterfly. Oh ! how Ave wanted 

 to look inside and watch the marvellous changes going on. How was 

 it all effected ? No doubt many of our readers in days gone by have 

 felt the same keenness for the acquirement of this knowledge. Well, 

 recent biological research has laid all this open and plain before our 

 eyes. The German Professor Weissmann can show you the imaginal 

 discs in the larva, which later develop into folds, and which ultimately 

 become the antennae, eyes and wings of the imago, and you can 

 follow the growth of these by wonderful sections through the pupa. 

 The serial section cutting, by means of the microtome, has enabled 

 us to follow the processes of Nature by which these changes take 

 place to an extent little dreamt of by our scientific ancestors. 



But in many of the transparent aquatic larvae, by careful preparation, 

 staining, and mounting, the imaginal discs of Weissman can be clearly 

 made out, now that we know what they are. 



In the plate" which accompanies this number we present our readers 

 with details of the larva and pupa of Corethra plumicomis, the well-known 

 Phantom Larva, which no doubt many who are fond of pond-hunting 

 have captured, and watched with interest whilst making its curious leap- 

 ing jerks. It looks like a transparent rod of glass, with two black spots 

 on it. These are the air-sacs which enable the larva to poise with such 

 certainty, but they greatly add to the difficulty of mounting these larvae, 



* We have to thank our friend Mr. A. Hammond, F.L.S., for the beautiful litho- 

 graphic plate which is drawn from nature, except Fig 5., which is a reproduction of 

 Weissmann's drawing. The natural size of Corethra is twc-thirds of an inch. 



