7C8 Extracts from the Minute- Book of the Linnean Society. 



of the abdomen had been occasioned by the exhaustion 

 of the aeriform fluids it contained. To detach them 

 from those stations, the employment of a small degree 

 of force was found requisite. 



In prosecuting this subject, clean " pliials of trans- 

 parent glass, containing spiders and various insects in 

 the larva and imago states, capable of walking on their 

 upright sides, were breathed into till the aqueous va- 

 pour expelled from the lungs was copiously condensed 

 on their inner surface. The result was remarkable. 

 The moisture totally prevented those animals from ob- 

 taining any effectual hold on the glass ; and the event 

 was equally decisive if a small quantity of oil was sub- 

 stituted for the aqueous vapour. A similar consequence 

 ensued also, when the flour of wheat, or finely pul- 

 verised chalk, or gypsum, was thinly strewn on the 

 interior surface of the phials, the minute particles of 

 those substances adhering to the tarsal brushes of the 

 spiders, the pulvilli of the perfect insects, and the 

 under side of the feet of the larvae. These facts, far 

 from corroborating the mechanical theory, appeared 

 quite inexplicable, except on the supposition that an 

 adhesive secretion is emitted by the instruments em- 

 ployed in climbing. The next point to be determined, 

 therefore, was whether spiders, and insects in the larva 

 and imago states, when moving in a vertical direction 

 on clean glass, leave any visible track behind them. 

 Careful and repeated examinations, made with lenses 

 of moderately high magnifying powers, in a strong 

 light, and at a favourable angle, speedily convinced 

 me that my conjecture was well founded, as I never 

 failed to discover unequivocal evidence of its truth ; 



though 



