236 APPENDIX. 



into constrained and unnatural positions, and injured 

 themselves by struggling-. 



At the period the drawing's were made, it is proper for 

 me to observe, that the happy method of preserving 

 aquatic insects in Canada balsam or varnish was not 

 discovered; still, however, a live subject is far superior 

 to a dead one, under any circumstances whatever ; which 

 proposition I consider so self-evident that I shall not 

 set about proving it. 



] suspect that other individuals have met with the same 

 obstacles as myself in making drawings of living micro- 

 scopic objects ; for I think it may be affirmed, without any 

 illiberality, that, with very few exceptions, those of my 

 predecessors are proportionally more rude and incorrect 

 than those of any other subjects of natural history what- 

 ever; their various lineaments and features being fre- 

 quently false, and exaggerated to a degree amounting to 

 caricature ; nevertheless, they have been handed down 

 from one bookmaker to another, ever since the days of 

 Swammerdam, as if they needed no improvement what- 

 ever. I have made my drawings at that period of the 

 growth of the larva or crysalis in which I thought it 

 made the best and most interesting object, and that they vary 

 greatly in their appearance, according to the degree 

 of maturity to which they have arrived. There are also 

 many varieties, very closely resembling each other, which 

 it is not very easy to particularize ; but I am quite con- 

 fident;, that when the genuine object is procured, in the 



