THE GREY LOCUST 313 



wing-case ; but how different from the mature structure ! 

 The disposition of the radiating nervures, the skeleton of 

 the structure, is not at all the same ; the network formed 

 by the cross-nervures gives no idea whatever of the com- 

 plex final arrangement. The rudimentary is succeeded 

 by the infinitely complex ; the clumsy by the infinitely 

 perfect, and the same is true of the sheath of the 

 wing and the final condition of its contents, the perfect 

 wing. 



It is perfectly evident, when we have the preparatory 

 as well as the final condition of the wing before our eyes, 

 that the wing-sheath of the larva is not a simple mould 

 which elaborates the tissue enclosed in its own image 

 and fashions the wing after the complexities of its own 

 cavity. 



The future wing is not contained in the sheath as a 

 bundle, which will astonish us, when expanded, by the 

 extent and extreme complication of its surface. Or, to 

 speak more exactly, it is there, but in a potential state. 

 Before becoming an actual thing it is a virtual thing 

 which is not yet, but is capable of becoming. It is there 

 as the oak is inside the acorn. 



A fine transparent cushion limits the free edge of the 

 embryo wing and the embryo wi ig-case. Under a 

 powerful microscope we can perceive therein a few 

 doubtful lineaments of the future lace-work. This might 

 well be the factory in which life will shortly set its 

 materials in movement. Nothing more is visible ; 

 nothing that will make us foresee the prodigious network 

 in which each mesh must have its form and place pre- 

 determined with geometrical exactitude. 



In order that the organisable material can shape itself 



