PREFACE 



TO THE SECOND EDITION. 



THIS volume is a new edition, or rather a new work, 

 and fraught, it is hoped, with renewed interest, from 

 the increased number of facts and recorded phenomena. 

 Much has been expunged that was, on reflection, pre- 

 sumed to belong more naturally to another branch of 

 science, or at least made the question too complex and 

 abstruse ; such as the preliminary remarks on Light, 

 which might generally be supposed extraneous and 

 irrelevant. Subsequent researches and more ex- 

 tended experiments have also enabled me to modify 

 and enlarge my remarks, or fortify and confirm my 

 previous conclusions. 



The least agreeable part of my task is to combat the 

 opinions of those from whom I differ. I allude here to 

 the paper of Mr. Black wall in the Linnean Transac- 

 tions on the ascent of the gossamer spider, and the 

 subsequent controversy to which it gave rise, and to 

 Mr. Rennie's Remarks in " Insect Architecture." 

 My views on the principles by which the gossamer 

 spider effects its ascent, possessed as they were of 

 novelty, and published long before Mr. Blackwall had 

 ever turned his attention to the subject, could not be 

 expected to run the gauntlet of public opinion without 

 scrutiny, and accordingly they have been canvassed 

 and questioned. I trust it will be found that the facts 

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