THE DESCENT OF MAN 63 



white ants. You saw a diagram of it during my 

 first lecture. It presents the peculiar feature of hav- 

 ing for a short time, whilst it is passing through 

 the stenogastric stage as a full-grown insect, genuine 

 veined wings in the still cuticular appendices to the 

 thorax. 



I could scarcely believe my eyes, when I noticed 

 this for the first time in my series of sections. 

 Subsequently these little hooked appendages to 

 the thorax grow into horns, and serve as organs 

 of touch and exudation, and enable the fly to 

 balance itself, and no trace of likeness to wings 

 remains. Probably we have here a certain amount 

 of reproduction of the growth of some ancestors. 

 Originally these appendages developed into true 

 wings, now the rudimentary wings change into 

 other organs, serving quite another purpose ; but 

 as this change is not so remote, we still find a 

 temporary reproduction of the former winged stage, 

 when real wings appear for a short time. There is 

 no trace of wings in the Termitomyia, which has 

 departed further from the diptera type. In it 

 the hooked appendages on the thorax appear at 

 once, without any reproduction of an intermediate 

 stage. 1 



I might refer to a number of similar instances, 

 but what has been said will suffice to show that 



1 Cf. 'Die Thorakalanhange der Termitoxeniidae, 3 Proceedings of the 

 German Zoological Society, 1903, pp. 113-120, and Plates n. and in. Also 

 Modern Biology, pp. 390-392. 



