PREFATORY NOTICE. 



THE present work by Professor Weismann, well 

 known for his profound embryological investiga- 

 tions on the Diptera, will appear, I believe, to every 

 naturalist extremely interesting and well deserving 

 of careful study. Any one looking at the longi- 

 tudinal and oblique stripes, often of various and 

 bright colours, on the caterpillars of Sphinx- 

 moths, would naturally be inclined to doubt 

 whether these could be of the least use to the 

 insect ; in the olden time they would have been 

 called freaks of Nature. But the present book 

 shows that in most cases the colouring can hardly 

 fail to be of high importance as a protection. 

 This indeed was proved experimentally in one of 

 the most curious instances described, in which 

 the thickened anterior end of the caterpillar bears 

 two large ocelli or eye- like spots, which give to 

 the creature so formidable an appearance that 

 birds were frightened away. But the mere ex- 

 planation of the colouring of these caterpillars is 

 but a very small part of the merit of the work. 

 This mainly consists in the light thrown on the 



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